I seem to have laser lock on this subject... not sure why... just ‘cause I can.
Prices (approx) for various radial M/C. Some of these units have adjustable ratios which is very cool. You can tell by the cost.
AP = $595.00
ISR = $400.00
Spiegler = $499.00
PVM = $390.00
Brembo = $230.00
One thing to consider is the cost of the brake and clutch M/Cs combined. It seems the less expensive products charge a lot more for the clutch master, pushing them closer in total cost to the more spendy units.
The upper end M/Cs make the Brembo look like a POS.
I'm sure there are other M/Cs I've missed.