Spoke to a coup[le of breakers last week while trying to replace my dinged front wheel. Got quoted £140 for a s/h front without disc, for a wheel that is identical to the 750/900/etc. The rear is specific to the 600/750 at 4.5". 30 pairs......, 30 sets of discs......
I'm absolutely sure it would be safer and much more fun to run wets, warmers and decent dry tyres, but I know I'm not the only one that is already feeling the pinch without the added expense.
Now watch me stuff it on the first wet day!!
Ali