Even thou the Mirage 8 inch sub may be good I believe its to small for the size of room you have listed. Do you have a budget in mind?
Heres a few questions that need to be asnwered...
2) Do you use it primarily fot HT or Music? andbot what percentage...such as (80 HT/ Game & 20 music ? )
3) Is size a matter? ( Such as diamentions? )
4) Color prefernace? Gloss, flat, Black, Wood?