In reply to Aigen:
I posted them from NYC, not the UK, and it cost me about $20 for four cams in a box IIRC. According to the Royal Mail website a 2kg parcel is just £16.49 sent abroad. 5kg is only £1 more. Mountain Tools details return postage rates on their website.
There is a way you can thread a short sling onto the cam. It's a larks foot but the sling doesn't press on itself so it should work ok.
I would use this service again, but if buying new cams I would get Black Diamond or, more likely, DMM. Wild Country cams are effectively more expensive in the long run because of this.