Steamworks is a very good way of getting a ton of amounts and can even cover the majority of items you'll use in hunts. A quest I use to get the fuel is the event quest, "A Farewell to Zinogre", which has you fight... well Zinogre with the loot changing almost exclusively to Coal.
With this method, you can get hundreds of Potions, Tranq Bombs, etc. Doing one quest should give you just enough to fuel to do a full session of the Steamworks set at 10x output which simply gives you 10x the items at the cost of 10x the fuel.
Items you may not get directly through the steamworks, you can get via the melder with Steam Tickets like Drugs, Traps, etc., which you also get a ton of so go wild with them!

Maybe the only items that aren't too reliable with Steamworks are armor spheres, which you can get a ton by doing the event quest, "Brand New Brute", which like the previous mentioned quest, has you fight a Brute Tigrex that changes the loot to be armor spheres. While it only covers armor spheres, you can obtain a ton of True and King armor spheres with some repeated hunts of this quest.

Hopefully these two methods help get you a ton of items while still only having to hunt certain monsters instead of expeditions or Guiding Lands. If there's other information or changes I should make, please let me know. :)