ICEpower Amp Parts Express - $98

http://www.parts-express.com/bang-olufsen-icepower-250asp-power-amp-module-1x220w-at-4-ohm--309-250

These are on closeout at PE, and I've used these modules to build a DIY amp, as well as they are used by many powered speakers and subwoofer manufacturers.

"The ICEpower250ASP integrates a conventional power supply and a 250W RMS amp all into one highly compact, state-of-the-art performance, lightweight board. This powered amp board gives you a great start in building your own powered subwoofer, or active speaker system."

309-250_HR_0.jpg