On October 29, 2013 Amazon officially launched its Kindle MatchBook service, allowing customers to buy a heavily discounted Kindle copy of physical books they had purchased from Amazon. Prices ranged between free and $2.99. The e-books could be read on Kindle, Android or iOS applications using the free Kindle app.
Amazon said that 70,000 books were enrolled in MatchBook at launch, that more books would be added to the program every day, and that book detail pages would list when specific titles will support MatchBook.
"Amazon combs through your entire order history going all the way back to 1995, so the initial list of ebooks offered to you may be longer than you'd expect. And since they're full-fledged Kindle copies, all of Amazon's signature features including Whispersync and X-Ray are included. To see which of your past purchases are eligible, head to Amazon now" (http://www.theverge.com/2013/10/29/5042058/amazon-launches-matchbook-offering-cheap-digital-copies-of-print-books, accessed 10-29-2013).