Thanks for the info guys, I am gonna keep an eye on the classifieds here as well as on ebay. I saw the Alpine MRX-V70 go for $200 on ebay last night, so I am slightly leaning that way.
I just bought an Arc Audio XXD5080 for $130 shipped off ebay. It is tiny, weighs almost nothing and retails for $380. It is lightweight and sounds equivalent to the Class AB Memphis monster amplifier I had installed before. I think there is still one more available on eBay right now.
Massive Audio Nx5
about the only 5 ch I see in that price range worth looking at:
MB Quart ONX4.80 ONYX 4-Channel Car Amplifier/Amp
MB Quart ONX1.1000D - ONYX Class D Monoblock Car Amplifier/Amp
Refurb Cadence United Series Boston 5 Channel Class AB 1600 Watt Car Amplifier 812902007304 | eBay
korean made amazing amp, their top line direct from cadence
For those interested, I ended up with an Infinity Kappa Five, 5 channel amp.
Feel free to critique my purchase. :)
SInce the OP noted the RE xtx500.5 , i figured i'd write briefly.
It has now been discontinued, but can still be found at places for as low as 190 dollars or so.
I am very happy with it for a full-system amp. It isn't a powerhouse, so you should get _relatively_ efficient speakers- but i cannot complain about the sound or the size.
I mounted it to the underside of my passenger seat in my subaru forester.
My webpage has pictures of the guts of it compared to an old-school audio art 260.6xe, as well as pictures of the install, and other info about the amp:
www.c-j-l.net/Home/audio/subaru_stereo_installation_full]subaru_stereo_installation_full - Useful-Info