I've got 3 computers, running cases by Chieftec Dragon, Antec 900, and Thermaltake Eureka. I've had the Chieftec Dragon for several years and its a great mid tower, fitting a HD 4870 with ease. An example can be found at http://www.atxcases.com/products/productdetails.asp?main_catid=1&catid=88&prodid=68.
With a cost of $75, its a cheap case, yet it does its job well. The only bad part is that it fits 80mm fans instead of the newer 120mm fans.