In trying to match the HP Z8 G4 Workstation, which appears to be what's pictured on screen there, to the approx config of the Mac Pro, the closest two CPUs appear to be the Xeon Gold 6134 (3.2GHz 8-core, 3.7GHz Turbo, 24.75MB cache) and Gold 6144 (3.5GHz 8-core, 4.2GHz Turbo, 24.75MB cache). Both of these appear to be enormously expensive, so it's looking to me like the CPU is what's causing this giant price tag on the new Mac Pro.
If you look at the price of a 2nd one of these in the Z8 (shame Mac Pro only has 1 socket...) to get an idea of its "raw" price— rather than upgrade price from base CPU— you get $4520 and $5920, respectively. I have no idea why a modestly clocked 8-core CPU should cost so much (massive PCIe bandwidth? ECC memory channels? cache?), but I guess I'll start looking into that. Further, I don't understand why we cannot *also* have the great expansion and configurability of this impressive Mac Pro redesign, coupled w/ processors that are less stratospheric in price.
If the Mac Pro's CPUs are indeed in this (costly) ballpark, it certainly makes the rest of the system not seem so expensive. But still then, why are the CPUs SOOO expensive? And why no cheaper alternatives for people wanting something expandable but more in line w/ the cost of past Mac Pro offerings?