You want rackmount or an actual head? The 5150/6505 series poweramps are brutal, and you can get one in a Peavey Windsor, within your budget. Rackmount wise you could always look at the Carvin TS100, but that is just a hair out of your budget.
Personally I really wouldn't recommend getting a Solid State power amp for a modeling preamp, tonally speaking, a tube power amp will help pump life into the digital modeling, solid state amps sound stale and undynamic by nature, you wouldn't want to add more of that to the mix.
FWIW, I have an Avatar G412 w/ V30s and a 5150, will be getting an AxeFx in the future for some modeling as well.