Power Meters / Powermeters (SRM, Powertap, Quarq, Ergomo, Vector, Stages, power2max, P2M, 4iii, InPower, Cinch)

Ah, didn't know that. Presumably the cost of making very low-run removable spider chainsets is also pretty monumental, so it wouldn't make sense to sell such expensive cranks with the cheaper PMs.

I can;t recall now but I think SRM machine off the spider from 7900 cranks in order to offer the Dura Ace SRM, obviously that's not an attractive prospect with carbon fibre hence the need for Campag to make them itself.