Fruit Trees are incredibly useful, as once they are fully grown, they produce at least 1 fruit every second day when they are "in season"

(Fun Fact: Fruit Trees not only grow in the greenhouse, but don't need to be planted in the dirt if planted in the Greenhouse!)

Thing is, Pierre charges A LOT for a single sapling. Luckily, the Travelling Merchant offers a chance to not have to pay so much. There is one slight problem with this. Y'see, it's possible to get overcharged on these already-expensive trees.

SO, here's a list of all six trees, how much they cost if bought from Pierre or the Travelling Merchant and what bundles/quests they may be used in.

Apricot
Pierre - 2000
T. Merchant - 1500 to 2500
Spring
Emily wants one on the 6th of Spring, Year 2
Artisan Bundle

Cherry
Pierre - 3400
T. Merchant - 2550-4250
Spring
Artisan Bundle

Orange
Pierre - 4000
T. Merchant - 3000-5000
Summer
Artisan Bundle

Peach
Pierre - 6000
T. Merchant - 4500-7500
Summer
Artisan Bundle

Apple
Pierre - 4000
T. Merchant - 3000-5000
Fall
Artisan Bundle
Fodder Bundle

Pomegranate
Pierre - 6000
T. Merchant - 4500-7500
Fall
Artisan Bundle
Enchanters Bundle

Sashimi is awesome. Out of all all 27 giftable characters, only five villagers dislike it in some way. It can be profitable if you use the right fish. It is the subject of the most profitable quest.

To begin on the path of the Itamae, one must befriend Linus and have an Upgraded house. Sashimi is best made with the following fish. (Note that this isn't taking into account Fishing boosts, as most of the time I go with crab-pots)

Anchovy
Bream
Carp
Chub (not gold)
Cockle (not gold)
Ghostfish
Herring
Mussel
Oyster (not iriduim)
Perch (not gold)
Periwinkle
Rainbow Trout (only bronze)
Red Snapper (not gold)
Sardine*
Shad (only bronze)
Shrimp (only bronze)
Smallmouth Bass (not gold)
Snail (only Bronze)
Sunfish

*Sardines are probably better used to make Dish o' the Sea than Sashimi

At a certain point (21st of Spring, Year 2), Pierre will post a request asking for Sashimi. What makes this different from George wanting an Iron Bar to rub on his bad knee is that instead of the reward being ludicrously large for what it is. Pierre apparently needs Sashimi so badly, he's willing to pay 1000 gold for a single plate. Sashimi sells for 75g a plate. That's 13.333... times the usual amount.

Alright, You've found the strange box in the tunnel and fed it a cylinder of tamed lighting. You've grown some Beets and instead of shipping them or turning them into white death, you shoved them into First Citizen Lewis's fridge. You've either waited until Summer or have shoved enough Strawberries into Demetrius to get your hands on a Rainbow Shell and fed it to the mailbox at the station. You've obtained a fragment of Sol Proxima's radiance and fed it to the Sand Dragon. You've checked your (purely ornamental) woodpile and discovered a membership card for the Casino.

Now what?

Well, you've got a few options.

Buy some Qi coins. You'll need them. I'd suggest about 300 or so.

I don't reccomend the CalicoJack tables just yet. It's either 1000g per hand or 10,000g per hand. If you have enough gold to be blowing 10,000g per hand on a modified Blackjack game, you may as well be rich eough to buy that statue that the guy is offering (When you comfortably can afford it, DO IT!, as that statue spawns either Iridium Bars, Omni Geodes, Gold Bars or Diamonds on days where no-one has a birthday. On days where someone is celebrating another lap around Sol Proxima, it spawns a Loved Gift for them. Admittedly, it is a Bronze Quality version of that gift, but +640 Friendship Points is nothing to sneeze at)

No, what you want to do is play those slots.

Unlike real life, the slots in Calico Desert follow a pattern.

16 losses, win, loss, win, loss, win, loss, win, then 14 losses in a row, win, loss, win, loss, win, loss, win, loss, win, then another 14 losses in a row, win, loss, win, loss, win, loss, win, loss, win, then the cycle starts all over again.

I told you to get 300 coins solely so that you have at least 100 coins once you make it through the initial 16 losses

I'd suggest getting something to keep track of your losses, like one of those counter things that ride attendants use to know how many people are on a ride.

"But [INSERT CURRENT DISPLAY NICK HERE], doesn't Luck play a part in this?"

Kinda. Y'see, the slots will occassionally throw you a bone in the form of one of the smaller wins. The higher your current luck, the more often this will happen and the better the prize.

"But [CHARNAME], WHY am I gambling away all the money I painstakingly made farming Blueberries?"

The Casino does have a few things that you can't get elsewhere, like a spiffy top hat, some kinda dark paintings and a Rarecrow. This rarecrow is unique, in that it can equip hats. There's also the ability to buy Magnets, Hardwood Fences and Farm Totems, but, quite frankly, you should be able to MAKE these for a lot cheaper than what the Casino sells them for (Remember to add an extra 0 on the end to convert the price from Qi Tokens to Valley Gold)

"How does CalicoJack differ from regular blackjack?"

Apart from there being no suits (cards just have a number from 1 to 11 on them), not at all.

There are three merchants with shifting stock. Since the Travelling Merchant has a ridiculous amount of potential stock and no permanant stock, I'm leaving them out of this, bar to say that you should ALWAYS buy the rare seed when it comes up and to buy fruit trees when they sell them for lower than Pierre does.

The other two merchants actually require a little more effort to find. Sandy lives in Calico Desert, which is a bus trip away. Problem is that the bus apparently broke down after it delivered you to the Valley and, despite it being the Mayor's job to ensure that infrastructure is working, YOU have to resolve this issue in the finest capitalist tradition.

By throwing money at it.

It doesn't matter if you've sided with Jojacorp Synernests Inc (Joja Corp: Imagine a Smiling God) or with the apple-sprites, you throw money at the problem. It's actually cheaper to side with the apple-sprites due to the 5000g Membership Fee that Jojacorp demands. Without that fee, Joja is cheaper by 2,500g, but you don't get 3 chocolate cakes, 30 Quality Fertilizer, a Lightning Rod and a Crystalarium, which can pay off quite well.

Regardless of how you fix the bus, once you fix it, Pam actually has a job again! She drives the bus to the Desert. (She kinda sucks at it though, as you have to wait until 10 AM for her to arrive at the stop) Once you get to the desert, you'll find Oasis, where Sandy lives her solitary life (Pay no attention to the man in the black suit) Sandy sells seeds and one rotating slot depending on the day.

Maniday, she sells Coconuts. Don't bother. You can find them just lying around outside
Tyrsday, she sells Cactus Fruit. Again, Don't bother. You can find them outside or grow your own once you have a Greenhouse.
Wodensday, she sells Omni Geodes. This one, I'm kinda on the fence about, because on one hand, it's unlimited Omni Geodes. On the other hand, it's 1000g per geode that you won't make back from cracking it.
Thorsday, she sells Deluxe Speed Gro. Don't bother, as you can definitely make it cheaper by using all the cheap fish you have not used while training to be an Itamae
Freysday, she sells Honey. This can be fairly useful if you either don't have a bunch of hives and flowers set up or don't want to waste your precious Fairy Rose Honey/Opium Poppy Honey on crafting Farm Totems and Mead. That said, unless you have the Artisian perk, you are not going to make a profit from turning honey from Sandy into Mead (Unless you cask it, but I'm more focusing on profit sooner rather than later)
Surtursday, Sandy sells Quality Retaining Soil. On the fence here again. On one hand, QRS can be fairly slow to craft, as you are limited by the amount of tapped pine trees and coral found. On the other hand, water retaining soil is somewhat useless once you get Sprinklers
Sonnsday, Sandy sells Icecream. It's a fairly safe gift to give, barring Emily (Ovo-Lacto vegan), Krobus (Dislikes overly processed foods), Willy (If it doesn't contain Fish, Willy doesn't want it. He'd probably blue-screen if he was offered Fish Ice-cream) and Leah (Prefers to live healthily)

The other hidden merchant is found in the sewers. In order to get access to the sewers, you gotta dig, boy!

No, I don't mean "Break a sewer pipe".

Gunther (Y'know, the laziest librarian to ever don the glasses) has the key to the sewers in the library vault. In order for him to give it to you, you need to fill the museum.

(What is it with authority figures in Farm 'em ups/Life Simulators who think "Hmm, I should build a museum and expect the public to donate stuff to fill it")

In order to fill the museum, your best bet is to dig up the wiggle-worms you see lying around. If you're lucky, it will be an artefact. If you're REALLY lucky, it will be an artefact you haven't already donated. If you're EXTREMELY lucky, it will be a dinosaur egg. (DON'T DONATE THIS!)

Another way to fill the museum is to mine in the mines. ("I mine in the mines and what's mine is mine" is a perfectly legitimate sentence and one of the best quotes attributed to a dwarf). You'll find gemstones and geodes. If when you mouseover a gemstone and it says "Gunther can tell you more about this", it means that you have not donated it yet. Do so.

When you have donated 60 items to the museum, the next day, Gunther will *gasp* leave the library to deliver the Rusty Key, which will unlock the Sewers.

Now, down in the sewers, there is little of interest. A door that you can't go through yet. A statue that demands 10,000 gold to respec one skill and a strangely non-aggressive Shadow Dude. His name is Krobus (which, in Shadow-speech, means "bridge crosser") and he sells things.

His permanant stock includes both fragments of Sol Proxima's Radiance and the Space Between the Stars, which can be useful for getting access to the Wizards basement and getting somewhat valuable gifts in the mail from one of two wizards who wear a cowboy hat. Krobus also has rotating stock, although his are more useful than Sandy's

On Montag, Krobus sells 50 Slimes at 10g each. That's halfway towards a Slime egg.
On Deinstag, Krobus sells 1 omni geode for 300 g. I'd say get this if you want.
On Mittwoch, Krobus sells a 5 of a random fish for 200 g each. Most of the fish are used in bundles. Some of them are used in quests.
On Donnerstag, Krobus sells 10 mixed seeds for 30g each. Up to you if you want to
On Freitag, Krobus remains silent, but still sells an Iridium Sprinkler for 10,000g. If you lack the means or the materials to craft one, go for it
On Samstag, Krobus sells 5 of a cooked dish for a price that ranges from 50g each to 500g each. I've written up which dishes are best value in another section, so I won't go into it here.
On Sonnstag, Krobus sells 10 bat wings for 50g each. Guess they all can't be winners, huh.

* A bug exists where Krobus will replenish his stock of limited items when you end a transaction with him. This can be useful if you want more of what he's selling to then use for other purposes.

As of the 1.4 update, limited stock items do not replenish when you close the dialogue window. No more easy slime eggs or massive amounts of omni geodes for cheap.

A minor trick to make some easy money involves buying certain dishes from Krobus when the price to buy them from Krobus is lower than the price Pierre buys them from you.

Since pretty much all the dishes are profitable when the price is 50g to buy (I think the only ones that even at that low a price, don't turn a profit are Fried Eggs and Tortillas), I'm only listing the dishes that make a profit when bought when the price is below 200g

Autumn's Bounty (350g)
Cheese Cauli (300g)
Complete Breakfast (350g)
Fish Taco (500g)
Dish o' the Sea (220g)
Lucky Lunch (250g)
Maki Roll (220g)
Salmon Dinner (300g)
Ruce Pudding (260g)
Rhubarb Pie (400g)
Red Plate (400g)
Pumpkin Soup (300g)
Pizza (300g)
Pink Cake (480g)
Strange Bun (225g)
Super Meal (220g)
Tom Kha Soup (250g)

A similar trick can be used with the Fish Krobus sells on Wednesday, if you have the Angler Perk. Out of all the fish Krobus can sell, only the Sturgeon and the Tiger Trout make a profit.

Now, you'd think that you'd be somewhat limited in how many Krobus will sell to you, right? Well, Krobus actually has unlimited stock, just not on display all the time. What you do is, you buy up the 5 Fish Tacos at 50g a pop, then, you end the conversation, only to start up a new one. Repeat until satisfied/you run out of gold, then go see Pierre and sell all that stuff to him for massive profit!

As of 1.4, the above trick no longer works, along with MANY of the other exploits I liked using. Damn You Eric Barone!