GlennO
Axe-Master
My definition of good is as neutral / flat as possible, and by that definition I'd overwhelmingly recommend the Sennheiser HD600's, which is right below the threshold of your budget.
I've tried a lot of different headphones and I'll second the recommendation for the Sennheiser HD600's. Not only do they have the flat response that is so important, but I find my ears fatigue less with them over long mixing sessions.