Michael Kors has some really nice cases and accessories for the iPhone 5. One great wallet case that was designed by Michael Kors for iPhone 5 is the Black python Iphone Wallet with Wristlet. For a Michael Kors case it isn't even that expansive and you can get it for around 55$ from amazon.
Its is overall a really nice wallet case and you can hold credit cards and cash inside together with your iPhone.
It is a great accessory and a wonderful way to protect your device.
More information: Michael Kors Iphone 5 Case