On related topic
I had KSports kit now for over 1.5yrs, 10k road miles, dozen or so track days (plus carlimits, pistonheads at Silverstone and even an action day). Used ECB Yellowstuff pads, now on Bluestuff.
After replacing pads before the last track day at Brands ended up with fairly noticeable vibration under heavy braking (particularly into the Paddock Hill bend from 115+ mph). Probably have not bedded pads properly so now a bit of pad material residue on the disks that does not come off (tried couple times on the m-way to re-bed), so the disks need to be skimmed.
The disks themselves show decent amount of wear, probably more than I would expect, but then I do overbrake so for others they could last longer. This said I expect they should last at least another year, which would take them to 15+k miles and about 20 track days in total.
I had a quick look at price for new 356mm disks - Raylands (J-hook style) would do them for £295, MTEC replacement (grooved) will be £290, KSports original disks from GSM Performance (grooved) £387.
I also don't think pads prices are materially different, I have previously confirmed that the pad size is the same as for one of AP calipers and then doing quick google compare it was not that much of a difference. I did like Yellowstuff, although the way I drive they last about 6-7 track days, but they are quiet and very good from cold, not too dusty either. I am yet to form my opinion of Bluestuff but they are certainly better when hot, ok from cold, but dustier, and I expect they would be wearing disks faster as well.