Not sure of the UK situation, but it COULD be something like this:
A: Pay full U.S. retail price;
B: Plus international shipping;
C: Plus X% import "bicycle" import duty (4%? 6%?). on the retail cost of the item (before shipping);
B: Then they ADD the shipping cost - On the basis that the item MUST be "worth" that amount (item cost + shipping) to the buyer; otherwise, why you be prepared to pay it?
C: Then VAT is charged on that total.
D: If you're unlucky, your friendly courier will complete the paperwork before the item even reaches you. Then either KEEP the item until you pay their fees, or deliver it and then surprise you with a tax demand 2 weeks later.
Easy to see why European retail prices appear to be so high compared to the U.S.
After all, you pay the FULL U.S. retail customer price; add international shipping; add import duty; pay VAT on the item cost PLUS shipping - And it can STILL be cheaper (and faster) than buying the same thing in a European shop.
Still, there's more to life than rampant consumerism, huh?
(Universal healthcare, for example
)