My first thought is that they would buy Square as it is a very Apple like design and Paypal just launched their square competitor: http://www.theverge.com/2012/3/15/2874647/paypal-here-credit...

They would have to compete at microtransaction rates to hang with Paypal or Amazon outside the native appstore probably unless they tack on some digital content/storage costs to get 10-30%, i.e. iCloud surcharge.