Marked down from 11...
You have to be pretty close to someone to get the selling to work out. If you're close enough to buy, then you should be able to sell.
A few other minor "bugs" is that it would be nice if the note and the rusty key disappeared from your inventory when their associated quests are completed. Also, I'm pretty sure that I had an item to feed the trolls, but couldn't see how to do that without eating the food myself. Maybe I should have tried harder, but it didn't seem that important since I had already "finished" the game.
Anyway, a great way to spend an hour even with the occasional glitch!