You can start off with just the mains and subwoofer first and add the other channels later. If you want to stretch the budget a little more, add the QS4 and go with a phantom centre.

Something like a pair of Axiom M3 or M22 and one of these subs below (bic/dayton) would be a good start. With a small budget like this, it is best not to stretch it to thin. You are better off buying better quality components at the time, and expand to the other channels when funds become available in the future.
I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne