I have an older Yamaha rxv 630 avr receiver that I use to push 4 ohm front speakers and, I think, a 6 ohm center (all diy speakers). My Yamaha pushes them fine, although I only run them at about half volume or less. A few months back, I purchased the Behringer A500, and, using the preouts on my receiver, use it to power my two mains.
My receiver does have a switch on the back for use with either 4 or 8 ohm front speakers, though. I've never (in the two years, I've used these 4 ohm speakers) had any problems with the avr heating up or any other problems. My A500 works just fine for me (but, I am not an audiophile, by any means). I think there are several amps out there in your budget that would do just fine (especially "pro" type amps, such as the Behringer. Also look at QSC and Crown and maybe others).
Best of luck, Frank