<font color='#000000'>Offhand i could think of the Pioneer VSX D811S which i think cost around $300.  It's a 7.1 BTW.  It has excellent features and source/format flexibility but has a lousy amplifier section that is rated at 1% THD at 1KHz,  not audophile-grade in my opinion.  But it makes a great preamp with its muliti-channel preamp output.  
You can try scouting for other brands like Yamaha, harman kardon, denon, etc, in the mid-price range and look at the back panel to check if there are 5.1 pre-outs.  Cheaper receivers may not have these.  Just my 2 cents.</font>