Amazon has launched a new service called the Amazon Kindle MatchBook. The service went live today and it allows customers to buy discounted Kindle copies of physical books that you have bought from Amazon.com in the past. The prices range between free and $2.99. Around 70,000 books have been added at launch. More books are being added to the program every day. Amazon will run through your order history going back to 1995 to determine cheap e-books that you can buy. Whispersync and X-Ray are included in those purchases. Click here to find out if your past purchases are eligible.