How tall is your ceiling in that room? The volume of the room is important.
Internet-direct brands that get recommended around here are SVS (svsound.com), Hsu (hsuresearch.com), Onix (av123.com), and Axiom (axiomaudio.com) - there are others, but they aren't coming to mind at the moment.
A good step is to e-mail those places and ask them which of their subs would work well in your room. I'm more familiar with SVS (on paper...I'm still waiting for first SVS to be delivered), and I believe that they have some units that will suit your room and your budget.