IPD is, FCP Grotton is cheaper. On calipers, that are heavy and require core return shipping often, I've been buying them from the local parts stores with success on several old euro cars, just eyeball them close when you pick them up.
I figure whoever reman's the calipers for one of them likely does more calipers than ATE or whoever does. Plus they are cheap and local. No doubt genuine OE remans (or new) are better, but one does not even see them often anymore.