With that budget don't shoot for a full suspension bike. I could be wrong here as I've been out of the hardcore bike scene for a while... There are lots of pieces/parts involved in a good FS frame and there is a reason why you don't see lots of them in the lower price points.
Last year I got a Gary Fischer Tassahara, a nice hardtail for the $$$.
Also REI has some nice in-house brand FS bikes that might work out.
Good Luck Shaggy!
