Neither FlightShop nor Virgin lists shipping charges on their respective web sites. (Probably because they assumed most of their business would be to UK travelers, Hah!) However, when I first tried to order from FlightShop, I received this followup email:
Thank You For Your Order ******
For all orders outside of the UK We send the tickets by UPS and the rate would be about 80 US Dollars depending on where you are in the States.
If you wish to book we will require a faxed copy of both sides of your credit card with signature, name address and total spend of passes required sent to fax number 0044 1482 646072. If you wish to cancel you booking you may do so via return email
Best regards
The Flight Shop
England
I wrote back to cancel and ordered the passes through Virgin, which charged me exactly the price of the tickets without any shipping or handling.
Steve