Well a friend has told me that an excellent app called Cube has made a Windows Phone app credit reader and all with no monthly fees just 2.5% per swipe less than Square! Even accepts AMEX cards so go try it out! http://www.windowsphone.com/en-us/store/app/cube-credit-card-terminal/258cc5d5-f676-42fc-8f69-2e3a904ae710