Most DJ's use active monitors, meaning they are self-powered, for near-range listening. The Behringer B300 sounds like a pretty good solution for your application. Visit behringer.com
Speakers like these are not neccessarly designed around awesome quality of sound, but rather high decibles and big bass.
If you can afford it, go with passive (not powered) 12" PA speakers with an 18" subwoofer (or two). You need powerful sound, far more then most of our home systems need to be, because they are intended for extremely high volumes and need to be durable.
I recommend the Behringer Eurolive series for non-active (you need to amp them, Behringer also makes amps, Crown is good too). EV is also popular, so is JBL.
Good luck,
-Chad