with the CPUs you listed that'd be pretty much spot on £40, and again it'd be buying more used components when I already have used components lying around. At that point I might as well buy some thing like this bundle from ebuyer which would get me a reasonable brand new processor and motherboard. I've watched a few component auctions, and even ones marked "untested" or "spares / repair" tend to go for pretty high prices. And as I've recently found out to my cost, motherboards are not a reliable used item to buy (unlike CPUs and memory, which seem to take a lot of mistreatment and still work fine!)...