A few options come to mind.
KEF- KEF Q900s up front, Q600c or Q200c Center, Q100s or Q300s for surrounds.
Subwoofer-something from HSU Research (VTF3 MK4 for example), SVS (SVS-12 or SVS-15), or Rhythmik (F12)
Pick up one of last year's models for the AVR such as the Denon 2112, 1712 to name a few.
Keep in mind you can score some deal on the KEF speakers from accessories4less.com
CMT-340SEs up front or the Sierra Towers
CMT-340SE center or Horizon to go with the Sierra towers
HTM-200SEs for surrounds
Rhythmik F12 or one of the other options previously mentioned
AVR, options mentioned above
If you check on prices you will notice that I've used most of your budget on speakers. If you went the Sierra towers route it's $2800 alone just for the front speakers and center channel. The CMT-340SEs are only $868 for the three front speakers and $300 for the rear channels. That would leave enough to get a nice subwoofer and AVR. You might be able to get the whole KEF package within your budget depending on current pricing. Another idea would be to start with the best 2.1 you can afford and upgrade as finances allow.
These are just two of many possible options. I'm sure others will chime in with good suggestions.