mushi: what are the prices for those amps? if they are close to rm500 or more, you are much better off bumping your budget to around rm800 and get a secondhand amplifer that usually goes for rm1500-2000 new. IMHO, a good amp starts from rm2000 new.
the drawback of buying used amp is warranty, history of the amp use (rough use, or repaired?), too old (capacitors due for change, ics and power supply deteriorated) and of course, nothing beats owning something new lah.
what is your budget? and what do you plan to use it with? what gears?
cheers.