I've just been quoted £6.40 posted for a set of stainless cap heads if any ones interested.
As for my own bike I've had a quote for all the above plus carb top, carb rubber(to cylinder block) rear disc, footrest hanger and a few other screws for £18 and some change ( Button head pinlock's almost twice the price of cap heads)
Kits are a rip off
Check out the price of fuel cap kits, massive mark up considering there's about a pound worth of screws in the packet (some are probably worth the difference if they are tapered or machined)