The best camera will always be a personal choice, for a bit less money then you spent I bought a used Nikon D60 and 18-55 lens from a camera dealer.
If you go private you might get the D60 and 18-70 Nikon lens (which everyone says is very good) within budget. There's also the Nikon D40X body which will be a bit cheaper.
But at the same time, you might want something older but higher end. Or you might pick up a Nikon camera and find it doesn't sit right for you.
I'm guessing you already take photos, tell us a bit about what equipment you're using and what you like to photograph. Why you need to step up from you current equipment. It will help us come up with better ideas. The trouble with dSLRs is there any many things you can buy to attach to them, generally a basic body and fairly ordinary lens is a good starting point. But if for instance you're into birds or motorsport you might need a longer lens form the outset. If you do gigs a prime lens (a lens that doesn't zoom) might be better.