Haven't played since S2, what items are worth something and how much?

In Diablo 2 it was quite easy.

30 PGM = Lem
2x Lem or add = Pul
2x Pul = Um
2x Um = Mal
2x Mal = Ist
,…

So prices were kind of static and went down after each week but you always knew that a Shako will cost you about 2-6 Ists after ladder reset and maybe about 1 Um after week 2.
Occu was always 2-3 Ist runes and after week 1 it was free item.

But now? How can I really know what items are worth at launch of a ladder?
If I find a Jah or Ber will it be only 50 million or 500 million gold?
Will Jah be more worth than Ohm or Thul?

Can I somehow set my default “loot” from main class I am playing to a different or all classes? Its kind of weird if I play Druid “only” and won’t be able to find other cool uniques for lets say Barb.

Trading is giving me a headache because I want to be as efficient as possible and farm what is required to get wealthy fast but it seems like no one really knows what stuff is costing and what to farm.

D2 ladder was basically creating a Sorc to farm keys and a Pala to get organs and torches. So in D2 you had a clear goal: farm torches very fast and sell fast and expensive so you can lean back after 3-4 days and chill and build whatever you want with Infinity, Enigma etc.

What should I farm here?

Nothing I would say.

We won’t know until people actually get these runes and start trading them. We’ll have to see how ‘common’ or ‘rare’ they actually are. They could be worth nothing because we just find them in abundance. Too early to tell right now what they would be worth.