The 12K and 24K services are normally the more expensive ones as thats when you need the belts unless of course tis a time thing and they're 2 years old (in which case wish them happy birthday but don't buy them a present, saves a bit of money
)
12K service should also include fork oil whereas the 6 & 18K will not.
Nelly at Cornerspeed did my last big service and did a damn fine job, and a few extras for somewhere in the region of £500
[Edited on 29-7-2005 by BDG]