I don't know about UK based sources, but here are some US based ones:
RP motorsports - $2042
Dali Racing - $2160
SoS - $2460
I would guess from memory at around $200 shipping from US to UK on a set of wheels.
if you get hit for customs charges (50/50 chance on USPS, almost guaranteed if using BAX or FedEx) you're looking at duty at 10% of the combined value of goods plus shipping, and then VAT at 17.5% of the total including duty.
good luck
oh, by the way, Volk have more orders than they can cope with and the word on the US forums is that lead times are stretching to 6 months on these.