The only thing we can do is give you the names of speakers in that price range. ALL of our rooms sound different. I can take my speakers to youngmoes or vince spot and they will sound different. I know the sound of my speakers but mixing at their spot would be different from mixing at mine. different room, different modes, different everything.
You MUST use your ears on this one dog. Now if MY budget were $300 i'd go for event 20-20's, alesis monitor ones or tannoy reveal.