The SB1000 is a great sub too, but a little light for me. I have a much bigger room. I can say that they do sound really good, but I'd want 2 of them.
Edit: A single SB2000 will give you more performance and dynamic power than a single SB1000, but 2 SB1000s, I think, would be perfect for you. Your budget doesn't really allow for it though. You could try the 1000 and if you don't like it you can send it back on their tab. They have a 45 day return policy. Shipping and everything, so it's risk free.