Just a few points..
four valve belts are quite expensive, i can't find my receipts but they are about £60 a pair. I would say £120 for a belt change is a good deal.
A big service inlcudes changing fork oil, brake fluid, checking and adjusting valve clearances etc etc and can take two full days. Taking out the forks and stripping them is a job in itself.
Belts are quieter than chains, thats why most cars have cam belts becasue they have to pass more stringent noise tests than bikes.