For cheap builds Ive had a lot of rosewill cases from newegg. Theres almost always a sale for a decent case 20$ shipped. Even the slightly more expensive ones seem to provide a decent value. Just dont trust thier PSUs (Ive never used one...but cheap PSUs are all bad).
And no matter how ghetto it may seem, those stupid CPU ducts actually work rather well. Why buy a 30$ aftermarket cooler when your not overclocking. A cheap 80mm case fan on the CPU duct is enough to keep any stock CPU cool.