M Tax is definitely a thing... however the aftermarket in my experience has been worse at gouging than BMW. I think if you have a 320d, you are fine and will get good deals on parts which your indy/RMI place can fit... but when you rock up in an M, the dollar signs light up. Even for tyres, BMW is normally the cheapest or second-cheapest for me (very close in price to what I get from a mate who owns a tyre shop).
I can speak for the M5:
The electronically controlled suspension is VERY expensive if you have to do it outside of plan (to the extent that converting to KW V3 is a far cheaper exercise)
Clutch pack I didn't think was expensive (even out of plan). However if your gearbox goes you are in for pain (as with any car these days really).
The turbo coolant lines I've had to do a few times but not unaffordable out of plan
Wheel bearings I would not lose sleep over either.
The discs last a heck of a long time. The pads are expensive but not ridiculous (you can get prices at third parties that are actually more expensive than the OEM brembo pads)
Sensors on any of these cars (M or not) can be annoying, but on modern cars it seems they are a lot better in terms of both cost and reliability.
I am not saying it is cheap by any means... but this is not ridiculously expensive all things considered. It is usually people who don't own these cars (or have made an uninformed purchase recently) that are astounded by these prices, particularly things that are not regularly replaced, and then through the perception of the internet, people think you regularly need to drop R90K to keep it barely running. Even the E60/6x which is notorious for expensive repairs and maintenance is not bad compared to other V10 exotic cars...
What I find funny is this warranty company highlighting the cost will almost certainly actively try to strand you up the creek without a paddle when they are asked to pay out. Either way, 90% of M3s will not have CCBs... I think it wouldn't have been as annoying if he said it was R35K for a brake job. Does the warranty even pay out R90K for the discs if they require replacement? Or will they say it is 'abuse' as it is lifetime use? :roflol: If you do need the CCB discs under plan (I believe they weigh them to check), they do replace them.