Are you up to building one yourself?
you can hardly beat
http://www.chipamp.com or
http://www.audiosector.com amp kits, i have built many and they always work right away.
those national semiconductor chips are the same thing that are used in most powered monitors, including the Event 20/20 bas which i have.
well you probably are not, and have better things to do with your time than tinkering with electronics

, so:
You could just get a decent used stereo amp, 75 watts or more. as long as its not some modern "home theater" junk.
you can usually tell junk because they have things like "dsp sound effects" and other bells and whistles.
you can usually find various reviews and opinions of almost any amp before you buy it, and make sure it works, or there is a warranty
If you have to have a "studio" amp for not too much there is the alesis ra-100 and Hafler makes a few reasonable priced ones as well as the monsters.
If you want to spend lots of money then get a bryston

Very reliable and lots of headroom.
Also in the lower price range dont bother with "digital" or "class D" amplifiers. it is hard to get high wattage good with digital, and they are a bit prone to breaking (well peavy ones anyways)