http://www.truedisk.net
They charge $45 per disk to regrind rotors, plus shipping ($12.00 in a flat-rate box anywhere in the USA - up to three rotors can fit). Drilling is extra, don't know how much (see below).
Background is that J.R. (CBX-tras) found these guys in his area in Michigan, USA. This is a sort-of cottage industry run by two full-time machinists, Tom and Jeff. They have developed a process that Tom says is explicitly NOT Blanchard grinding, but it grinds rotors while it continuously bathes them in coolant. Hence, it is one of the few processes that is safe for our stainless steel rotors. As Tom explained it, one of the reasons our rotors cannot be safely 'cut' (turned on a lathe) is because that process subjects the part to a lot of localized heat and stress, that stainless cannot tolerate. Not a problem with their process and they have now ground hundreds successfully. They will also grind other items like flywheels and the like, but they are making their name with moto rotors.
Here's before and after shots of my '80 CBX rotors.
Before -
After - Ground and drilled
A word about thickness. You will inevitably lose some. Here's how mine went, before and after:
Before After Min
F-R 4.8 mm 4.675 mm 4 mm
F-L 4.8 mm 4.681 mm 4 mm
R 6.425 mm 6.161 mm 6 mm
More background and disclosure: When J.R. pointed me in their direction I found their website very broken. I un-broke it for them and helped him to update some content and make it better for the search engines. It's still a little homely, but it works. In return Tom has ground my rotors for the cost of shipping. In any event, I would happily pay for his services, they do a great job, are really nice people and responsive, and turn them around in a matter of days, return ship via Priority Mail Flat Rate for $12. Great service.
N.