ANtec 300 $49.95 it has room for expansion, cable management space, dust filter, easily accessible intake fans , fair size and good cooling performance, all this getting the most bang for your buck.
i own both a rosewill challenger and an antec 300 and honestly i cant decide which i like better , you cant go wrong with either
I like the haf 912 as well, but its $10 more. My last build was with the challenger it was also a great case. In the end it comes down to preference (as long as it has adequate air flow/ the features you need) when selecting a case.