@David82, Do Not Give Up Too Soon
@djMax, I found Paypal reader here
, The reader looks cool, I guess it is OEM/Repackage of square credit reader.
The square reader is reverse engineer the iphone audio interface as well as iOS which would be a little a bit pain in the butt to use, the speed of swip and make sure insert it properly, and it only support one track of card.
In the other side
Arduino is able to connect the magnetic card reader/writer to read or write all 3 tracks of card, meanwhile Arduino support PayPass reader to read/write PayPass contact-less credit card, and it support contact reader to support ISO/IEC 7810 interface contact credit card.
All above of reader/writers could have bank industry certification. The writing function is in theory only, the reason is obviously.