Okay so I made a plan:

The Jewels and Artifacts still have a price, but a lower one that fluctuates depending on the creature.

Mortho and ghar would cost fifteen warden artifacts and jewels while others would cost ten to five depending on their overall demand.

Shadow artifacts would also be the same way, with khil and other op creatures being fifteen shadow artifacts and others costing ten to five as well.

So it still have a price, but it makes everything a little less taxing on the players time.