for the C-class you'll have top stick to 17inch or less and to find 17 inch AMG's is next to impossible. since anyone who could afford the rims either had an e-class or an S-class, both of which use 18's or more.
Which ones do you have on the car right now? and maybe i can guide you to a better looking set.
Also i should point out that the world doesn't begin & end with AMG,... there are other tuning housees out there whos rims are just as good looking.