I bought a CD on eBay. It just arrived in an Amazon box, with a gift receipt, along with six metal rings -- evidently for horse bridles -- also with gift receipts.
The only possible explanation is that the eBay seller didn't even possess the CD. They sent it as a gift to me from Amazon, and added the 75¢ rings to hit the free shipping minimum.
And I paid way more on eBay than I would have on Amazon.