I have been hearing great things about the AV123 subs. You might want to give the X-sub a look. I have a MFW-15 on order myself, but that might be too large physically for you room.
The SVS PB10 is supposed to ge a great sub too, but it's box dimensions are still pretty big.
Yeah, the more I think about it, I would say the X-sub from AV123.
Later,
Mark in GA