I currently have several target area amps with one in my second system being used on a fairly regular basis, a ML 23.5, main system has a ML333. At work I run a Bedini 100/100 and because it is one of the first amps I ever bought new, a Perreaux 3150 as standby. Any and all would come in below your budget, and most well below. I run all three stsyems with a tube pre (two ARC and one Quicksilver). Since the ML are att AB heat is not much of an issue, Bedini is A as I recall but does not run terribly hot and I have left it on days at a time.
My 0.02
My 0.02