Several places, prices depend on material and whether they are original Dzus etc.
Pro-bolt actually do some titanium ones at £12 each if you're wealthy. I got some chrome plated ones from Preformace Motorcycle Parts that did the job. Came with nylon washers and the clip part too in a pack of 8 for £12. Fast delivery, I'd use them again. I tihnk they were available in Cad plate too for the original look.
http://www.performancemotorcycleparts.co.uk/