In game item exchange

[Enkidoh]

Or.... pay attention and buy the right thing in the first place, not just faceroll it at the vendor.
Myself, I do item comparison, try ons, the works, before i'll commit to spending those hard earned tomes.

^This pretty much. It's the player's responsibility to check what they're buying is actually what you want. The common retail mantra 'all sales are final' and all that.