I have no idea how the Barnes & Nobles near you work, but mine does not care if you purchased an exchange from them or not, they never ask. I've even told them I received a book from out of state, made no difference.
As long as they stock it, and it's unread, they exchange it at 80% of value. They don't lose any money on the deal. Let's say I have a $10 retail book. I exchange it for a like priced book. They give me $8 credit, I pay them $2 and get the other book. They make $2 on the deal and they can always return my exchange to the publisher if they don't resell it.
Maybe it helps that I'm on a first name basis with everyone there.
Another one gone
Anandtech Moderator