It is $US55, however, the maker of this fine conversation piece says all of an Atari 2600 cartridge's parts, except for one screw, are repurposed to help make it into a wallet.
The maker, Nilesz, is running a win-a-wallet contest over on his site, which of course gives you the info on how to order one. From his blog, it sounds like he does take mail-in requests, but you need to make sure you're sending him something usable first. It'd be bitchin' if he could do the old Imagic cases, but the 14 he does offer - including Haunted House, Circus Atari and everyone's favourite, E.T. - are slick enough.