Halfords are good and you can extend the set quite cheaple through EBay buying one or two at a time, their ratchet spanners are also worth the money.
I wouldnt bother with Snapon unless you work in a garage, the only reason is although they are good the reason why they cost so much is if you work in a garage a rep will come round once a week and replace any tools that get broken , for free, this is what you are paying for. Halfords pro are every bit as good as snapon.