I've just been on the phone to the shop. They have "loads" of these glasses. They weren't willing to do a group buy unless all the glasses went to a single address and I for one am not willing to be the person to organise that. However, they have agreed to give a 50% discount on postage to anybody who identifies themself as a member of o-review.com and asks in the additional comments box on the order form for the discount on postage. You might be able to push for free postage if you take two or more pairs and probably be able to get it on a three+ pair order.
http://www.cyclestore.co.uk/productDetails.asp?productID=10383&categoryID=519