Want to know if you are looking at the deal of your life or if you maybe should wait for another sale?

There are indeed games which are cheaper in winter sale than in a summer sale and so on (marketing strategy I guess).

But you can look up the price history of every (as far as I have experienced it) game, dlc etc. on steam, under:

http://steamsales.rhekua.com/

made by Rhekua

I wish you many good purchases!