AT&T retail stores will be offering refurbished iPhone 3GS models to its prepaid GoPhone customers -- no-contract accounts that do not qualify for subsidized phones -- according to a MacRumors tipster. The iPhone 3GS was originally released in 2009 and, notably, will not run the new iOS 7 when it's released this fall. For comparison, AT&T sells the refurbished iPhone 4 for $325, so the 3GS would presumably be offered for well under $300. The tipster claims the phone will not be displayed or promoted publicly, but sales reps will be able to offer them to certain price-sensitive customers. Not all AT&T stores will have them but it is claimed that AT&T's larger and more metropolitan locations should have decent amounts of stock.