I'd pay a million tria for a pair of gloves like those that were in the tent where that alchemist was held. It seems to me that you could leech a lot of tria out of the game if there was one elite item merchant selling triple mod items of a type that cannot be looted. Of course then you run into the problem of unkillable PCs. This npc could even sell things with 100% markup and not buy anything. Your newly bought item would depreciate by more than 50% the moment you bought them but they would be meant to be used, not resold.
If gear wears out faster it would lead to a rise in the number of people who can repair it perfectly, thus ensuring it never wears out. Improving the quality of looted gear is probably not that good an idea, how much protection could I expect from my million dollar hat with the 26 slash value if I could improve it 6-fold? Would anything be able to touch me?