I like this. You would have to use gift cards in store to dispose of the cash, and even at $100 gift cards, you'd be looking at 236,987 cards to purchase before you can buy the book.

I used to have Play.com vouchers through my credit card and wanted to buy a new camera, only the listings were from dodgy sellers and £100 more than Amazon. I did think about listing an item, then buying it myself to convert it to cash.