What size are you?

I don't really know anything about these particular bikes, but the lower priced ones give you plenty of spending room to upgrade a couple things or put a nicer fork on them.
http://columbusga.craigslist.org/bik/2436082392.html
http://columbusga.craigslist.org/bik/2472299788.html
http://columbusga.craigslist.org/bik/2459749874.html

EDIT: Actually, the first one has a 63mm fork. Might be hard to replace that because there aren't really any nice ones available.