There isn't much to cases. You just need to pick one that fits the board and has good cooling (i.e. fans). After that, it's mostly quality (few plastic parts), locations of external ports and other preferences.
Off the top of my head, some good ones to look at that should be close to your budget would be the Antec 300 Illusion, Coolermaster Centurion 5, Coolermaster 690, and HAF 922. The HAF 922 is likely to be slightly above your budget, but it's easily the best case out there.