I'm from the UK so I don;t know how much computer stuff cost over there.
But I'm guessing from the replys you can't buy a decent premade onefor that amount.
If I were you I would build one from yourself.
The good thing about that you can choose which bits to put in there and when you get more money you can upgrade it!!
Just get a good motherboard,cpu and memory to begin with the rest you can by second hand (auctions) and when you get more money upgrade the other bits.
Building a computer is easy not as hard a you might think, go to:
HERE To get an idea of how its done.