We get ripped off on all PSU's except for Hiper - only because it is made in the UK - which is £65 but with that you get the best modular PSU, that is IMO the best looking (its like a sapphire (is it double P?))
For £40 there is the Enermax Noisetaker 370W, which will be good, and has enough watts for a beefy system, just not for the 6800gt and X800 series and above cards.