Bang for the buck in subwoofers is used, lots of folks downsizing from big places to little. I'm a total cheapskate, managed to get 4 powered subwoofers from Amvets for a total of $200. I've got one left, a little Sonance powered sub, mates well with my a/d/s 400 speakers, appropriate for my 9' x 10' x 8' bedroom. Set me back $50. Have to consider how much air is being moved in a given room, not to mention issues like neighbors in apartments, duplexes and condos. Had three powered subs in my garage studio, placed to accommodate the room's resonance modes—one corner placed sub would cancel out in the "sweet spot".