With a $900 budget for only the speakers (assuming 5 channels and a subwoofer), you can easily fill a 12x14 space with excellent sound. The problem becomes the space you're trying to fill.
First, is your budget of $900 for 5 speakers + subwoofer only? Do we need to worry about adding cable costs to that.
Second, what is your environment like? A simple MS Paint diagram would help a lot. Furniture, ceiling height, floor type (carpet or wood, hard wood or laminate). Do you share walls? Where is the door? IS there a door? Where is your current listening/viewing setup sitting? What's your viewing/listening distance from the front stage?
Third, do you have a preference for designs? Some people like the exotic looking wood cabinets, some people like piano black, some people like a hardwood grain look.
Zimbo is right, Hsu stuff is all good. They make good speakers and their subs aren't commodities. Most people could keep even the lowest Hsu sub for life.
EDIT: I quick thought made me think of this setup. Aperion Audio Intimus 4B speakers for front and rear sides, 1 Aperion Audio Intimus 4C center channel, and 1 Hsu Research STF2 (which I love for sounding like STFU since that's what you'll do when you hear how awesome that sub can be in a small room like yours). That should come out around your budget, and I know from experience it'll sound better than that Pioneer system. When it comes to speakers, bigger cabinets don't always equal better sound.
