amc makes a perfectly serviceable, bridgeable 2 channel ss amp which is generally available for $200 or so on ebay. i also see a bunch of used b&k st140 in that range. i'd also look at marantz ma monoblocks, which you should also find used within your budget. for a cheap preamp, adcom gtp or b&k are good products.
Best Used under $300 2 Channel Amp
WE ARE ON TIGHT BUDGET AND LOOKING FOR ADVISE ON A MIN.100WPC 2 CHANNEL AMP IN THE SUB 300 RANGE.WE HAVE SEEN ADCOM GFA 555,CARVER TFM-25,TFM-35,NAD 2400,2600.I AM A ROOKIE AND YOU GUYS ARE THE REAL PROS,,ALSO NEED STEERING TOWARDS PREAMP ALSO 2 CHANNEL IN THE CHEAPO DEPARTMENT.I WILL BE RUNNING 2 AMP BIAMPED TO MT NHT T5 SPEAKERS IF THAT MATTERS..THANKYOU///MARK