The launch of the iPad may have ironically helped Amazon improve the business model for the Kindle, Needham analyst Charlie Wolf found today. Amazon had previously insisted on a wholesale model that sold e-books at a loss but made a profit on the Kindle readers, but Apple's insistence on agency model pricing for the iBookstore may have done the online retailer a favor. By creating pressure on Amazon to switch its own deals at the risk of losing publishers, Apple has now forced Amazon to turn an estimated 30 percent profit on each book it sells, Wolf said.