Depends. An Alesis RA-100 could probably be had for $150 on eBay - that was a standard home recording power amp in the days before powered speakers.
Look at some powered monitors - they have appropriate power built in, are easier to use and and to set up. You'll probably wind up saving some money in the long run too.
if your a portable engineer actives would be better to carry around.
actives are the new way and easy to plug'play.
if done right actives are often superior at being technically matched- amp to speaker.
if your like me,no traveling or customers..
HR only.. songwriter / recording...passive and amp are nice too.
you can add in a speaker selector and have several monitors to select from
with a push of a button. passives are about 50% off too for future purchases.
I have:
SPKR 1: BW303 (6.5" @ 1meter)
SPKR 2: PARADIGM se (8" @ 2meter)
SPKR 3: JBL SUB
SPKR 4: OPTIMUS 7 (1meter)
SPKR 5: ??
SPKR 6: ??