Best brands from speakers within your price range are Wharfedale (IMO). I've blown ebnough through an over powered amp and under powered speakers to know (it's also cost me an amp through that mistake as well).
I've got a set of Wharfedale Diamond 9.0's (http://www.hifibitz.co.uk/product.asp?id=3429)
Punchy for there size, whilst still clear at high volumes. Great for all sorts of music from Punk,Ska to female soloists.