ID companies are the way to go, HSUresearch, SVSaudio, Rythmic, ect, my favorite is HSU, I have dual VTF2's {you can get a pair for around $1150 shipped} but you can spend much more than that... My room is a little over 400 sq ft with 9-12' ceilings open to a large hall way and a large kitchen...
As far as 2 subs or one, 2 sounds better 1 may do the job depending on the room size, your desired spl, and the sub of course...
good luck and welcome