I sent this information to another friend for his opinion. He responded:
A couple years ago I saw a girl in a small thrift store scanning CDs. I think she had a palm pilot with a UPC scanner on it. What I think she was doing was just scanning the entire inventory and then putting up all those items for sale on Amazon, and if the CD sells, she goes back to the store and buys the CD. That means that if it's already sold, then they have to cancel the order -- and I have had that happen to me with used books a couple different times at Amazon.