Speakers for the party system

Twice a year, we host a gathering of around 120 friends for several days. Across the years, we have gotten much better at supplying food, beverages, camp sites, showers etc. The issue is music for wild dancing! Until last year, we used the main floor of our house and our reference level sound system. Everyone was very happy but me... I always worried about spills, chills and expensive thrills. Last year, we finished the basement and moved the party downstairs. The room is almost the same size (900 sq ft), but with lower (9 foot) ceilings. I bought a fairly descent system, but the party girls wanted much more punch and thump. Can anyone recommend a reasonably priced speaker that will really fill this room with booty moving magic? I've noticed some good deals on PSB scratch and dent stuff but have never heard these. My main system uses Dunlavy V with Plinius SA-100 monos, so the competition is fierce. Song selection includes everything from Mikey Hart to Mojo Nixon, Parliment to Massive Attack, The Beatles to Lou Reed...