nurglespuss
Fish Gatherer
Look for sellers with good feedback
Everything is a risk unfortunately, I got stung for £40 on this site (not the forums fault - my own risk) with someone with good feedback etc.
Its the lure of the internet, you get so used to it being 'safe' you forget that you can get bad with good.
Just be careful, and if a deal looks too good to be true, well...