I don't see the point. As others have said, you have ample opportunity to check for yourself. There isn't a huge variety of gear at level 50 nor level 60 that would warrant a refund, and if you screw up, that's on you. Go farm more seals or tomes or whatever. It's not like there aren't confirmation boxes. I sure as hell haven't ever had this problem. Do you really want people to be able to, for example buy gear, raid with it to get better gear, then take back the first set of gear to get their money back?

This just feels like a non-issue that really doesn't require any sort of solution.