i have a memphis power reference amp thats 500 watts at 1 ohm but memphis really underrates their stuff (as you may know) and their amps are simply a work of art. I paid over 250 for it new and its still in great condition. Model number is Memphis 16-PRD500.1 . I can take pics and heres a generic pic: http://www.sonicelectronix.com/item_3006.html
It's at the top of your budget but it has lots of overhead for you //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif