Im in the same boat too. To be honest, youre gonna be really hard pushed to get anything decent for that price. Dont even bother going new, stay in the second hand market.
The best places to look are on ebay (locally) / gumtree / speakerplans forums.
That last one is the best, theres loads of stuff that comes up down in london, I just wish I didnt live as far away otherwise id've already picked stuff up by now.