Right, getting better - £262 from Peter James, if I'm a member of a bike club - any bike club but not a forum like GSer. However, VMCC is £47 and BMW Owners is £60, which wipes out a big chunk of the savings. Are there any cheaper clubs? I'm unlikely to participate, so this is just an exercise to get the premium down.
Also, I wonder if I'm being over-optimistic on value. For context, the bike is the Kalahari Basic that was the subject of Mikeyboy's recent rebuild thread. My logic of £17,500 was that that's pretty much what it would cost to replace, but an independent valuation is required anyway, which means more faff.