That said, I get to deal with the occasional "OK, now that our event is over I don't need this anymore, how do I get a refund" email. I eat all the costs on those and don't argue because there is no profit in arguing, but one can understand if I don't have those folks in my Favorite Customers Hall of Fame. You bought a book from a mom-and-pop business, got exactly what you were promised, and then -- because it was convenient -- reversed the transaction and stuck them with all costs. You're a textbook pathological customer. Do you understand why people might not want to work with you?
[Edit: Oh, the economics of the "dispose of it how you want" are fairly straightforward. It simply isn't worth restocking/shipping/admin overhead to take the item back. We had a similar canned line at the office supply store I worked at: if you complained your paper was "Made out of trees!!!" and that prevented you from using it, I would tell you to "Donate it to a local charity or otherwise dispose of it in any way convenient to you." Same thing with BCC disks: they're cheaper to print than to ship and if you hypothetically sent one back to the factory they would just destroy it and charge me for wasting their time.]