http://www.b-52pro.com/products/Matrix1000V2.html
That's my first suggestion. I'm not well versed on speaker systems myself other than researching what is good to start with, but that's been said to be one of the better ones that is powered, and comes with a sub. Would probably fall a little under your budget as well.
The other suggestion I would make, would be getting two QSC K12 tops. Should have enough low end to get you through (and if you really needed it, you could rent a sub until you can buy one). But you'll also have the BEST quality sound.