my build (see my signature) is a solid $600 machine. No overclock, but it doesn't need it.
With settings maxxed out, it gets 62 fps in APB Reloaded, 54 In Fallout 3 and Fallout 3 New Vegas, 24 in Second Life, 120 in DC Heroes Online, 55 in Bulletstorm, and 34 in the Unigine benchmark..