Short answer, yes, it's worth investing in a good case, up to a certain point. I wouldn't pay more than $150 for a case, because I know the benefits beyond that point are hardly worth the extra cost
And since it seems that recommending cases is the trend... on behalf of JohnnyLucky from the PC Case forum, I recommend the Lian Li Lancool DragonLord Series.
Those cases really are nice cases though, and not overrated like the Antec and HAF cases. The popular Antec cases all lack mobo tray cutouts, which are a must, IMO. HAFs lack fan filters, another must that ~$100+ cases like the Antecs and HAFs should have.
Personally, I would only consider the Lian Li DragonLord series, the CM 690 II Advanced, and possibly the NZXT Tempest Evo, all at ~$100. Or, if you need a bigger case, the CM Sniper rivals the HAFs in size and surpasses them in features (it costs $150, a bit less than the HAF 932). All these cases have mobo tray cutouts, fan filters, good airflow and cable management, beautiful black interiors (even if you don't care for a window), room for large HSFs and graphics cards, etc.