Ok, lets see here.

Allow $250-300 for a receiver from Marantz, Denon, Harman/Kardon, Yamaha, or Onkyo.
Allow about $100 for speaker cables and interconnects, probably a little less.
That allows around $600, maybe a little more for speakers. You could check out the Athena system at Best Buy. The HSU Ventriliquist system goes for around that much and includes a very nice subwoofer. Or, you could go to your local audio/video store and pick out a nice pair of speakers that sells for about $200 a pair. and buy three pairs, and you could buy the cheap partsexpress.com 100 watt 10" sub for around $130 I believe. There's a number of options out there, I personally would go with the previous option I gave you. Good luck.