[Polycaster]

There are 2 potential problems.
1. There has to be an empty slot for the item. Popular merchants get their slots filled quickly. If you sell an item to a merchant w/ no slots, it is gone.
2. Someone can come by and buy your item while you are selling the depleted items to be recharged. I seem to remember some drama about this on blue, where some people would lurk behind a guild going to recharge their items to scoop up a few.