Review on Men's Leather Wallet with Credit Card Holder and Money Compartment - Essential Accessories for Men by David Sanchez

Very strong magnet to clamp money in both directions! I think this is a plus as it's more handy than just a wallet, but it might be worth considering if you're dealing with anything that gets in the way of magnets. Otherwise, a basic, nondescript money clip/wallet will hold a few cards and remain thin, and the leather is fairly durable.