Raijintek Thetis
RioToro CR-1080
RioToro CR-1088
These are amongst the smallest cases that can accept full ATX gear (i.e. ATX mobo, ATX PSU, "Normal" sized CPU coolers, Full-sized GPU) that are reasonably priced (both are around $100). There are others as well but they start to get pretty pricey and/or compromises to parts (i.e. Lian Li 011 Mini requires the use of a SFX PSU).
Edit: I see RioToro now has the CR1088, a RGB version of the CR1080 if that's your thing. I prefer the RioToro over the Raijintek. I'm currently running the Raijintek Thetis and cooling isn't the greatest nor is the fit and finish. The RioToro doesn't LOOK as premium as the Raijintek but is a better performer and built better and will probably switch back to the...