Might want to look at PSB Alpha B1 at that price point. Monitor Audio Bronze, Wharfedale Diamond might also be considerations. The Definitive Technology, B&W, and SVS mentioned before are also good choices (might want to add Hsu Research to your list of subwoofer choices).
First, you need to decide if you're going with a 5.1, 6.1, or 7.1 system. My personal preference is to go with a 5.1, and putting the money saved from the extra surrounds into the other speakers. But if you're mainly into movies, you might want the extra surround speakers for effects. Second...