Maybe you could put a "warning", much like the alert when trying to salvage rare items or legendary items. The warning would be "You're attempting to sell a recently equipped item. Proceed or cancel?".
There are several more things we need to consider in addition to what I listed above, but I think you get the gist. :)
- Should the warning dialogue only appear when selling an item that's been equipped? What about the items that players just want to sell and haven't equipped?
- Or should the warning dialogue appear whenever selling an item of a certain quality level? If so, what quality level is appropriate? Should it apply to only Rares and Legendaries? Or should it apply to all magical items?
- If the warning dialogue appears when selling all magical items, would that then become tedious for players who farm a lot? If so, which is more valuable to the player: having a warning dialogue in addition to the Buyback option or having a quick way to empty their inventory?
- In other games that have warning dialogue and a Buyback tab, many players still mistakenly sell their items, so will adding it to Diablo III actually provide a better experience?