You have to stop thinking that a large OEM such as apple will be as subject to the artificial market segmentation pricing Intel & AMD makes. Intel sells i7 CPUs much cheaper than the equivalent xeon cpus for example. The big advantage of the equivalent xeon is being able to dual socket it and some other cheap-for-intel features being switched on. You can't dual socket CPU this mac pro anyway and GPUs tend to max out at ~$500 each for equivalent consumer GPUs.
So in summary, you can make an equivalent performance PC for $1500-$2000 dollars.
You misunderstand. I'm not thinking that Apple is subject to anything. I'm not talking about their costs at all. I'm merely talking about our costs if we were to try to build an equivalent PC ourselves.
Apple probably gets a steep discount on all of its components, but that's completely irrelevant for this comparison.
I don't doubt that you can build a much cheaper PC if you go through the whole parts list and substitute cheaper, worse consumer parts for all the workstation parts in the Mac Pro. The question is, can you really build the same thing for the same price? I bet you can't, or at least it's close. Maybe you can, I could be wrong.
The question isn't how much a generic PC that's "good enough" costs. The question is how much it costs "with the same parts".
You get ECC RAM, but mostly you're paying for drivers. They are usually slower for gaming, but provide better accuracy and usually crush consumer cards in pro performance.
It may be a marketing con, but if you buy your $30,000 engineering package and expect it to run on your gamer GPU, you may need to do some video card firmware hacking to make that happen. And then, of course, you won't be able to get any customer support from the software vendor for any visual glitches which may appear. Sucks, but that's how it is -- workstation GPUs _are_ better, generally not in terms of FPS in Crysis, but in terms of out-of-the-box compatibility with off-the-shelf high end software packages.
If you are in the rare software segment with $30k software, then the extra $1000 or $2000 to indirectly get hardware drivers & firmware that confirm with your $30k software is not a big cost.
BUT, there are large segments that do not need those special drivers in their software set and are restricted by circumstance to use OS X only, such as iOS developers. Or just people who want high performance GPUs with their mac who don't need the FirePro feature set. There are also many software packages that do GPGPU or OpenCL just fine with consumer segment GPUs too.
I would of loved it if it was a mac pro with dual CPUs vs. dual GPUs for example, something you really can't physically get without the xeon level chipset, even though we all know it's very possible with a consumer chipset.
I just remember that at my last work, the hardware designer was using Solidworks for his CAD work, and the single-threaded rendering was an issue. There was an active community looking for the best cards to do that rendering on, and moderately high-level gaming cards did significantly better than the 'workstation' cards by Matrox and similar.
I don't know what price tier Solidworks is in, but looking at their site now, it's in the "get a quote" category, so they're not a consumer-level bit of software.
Core i7s and Xeon E3s are actually very close in price. The E3 1275v3 is $353.99 and the i7 4771 (the same sans ECC) is $319.99, and the i7 4770K (no ECC but overclockable) is $339.99. The E3 1245v3 (100MHz slower) is only $289.99, and the i7 4770 (same base speed as the 1245v3 but one extra turbo bin) is $309.99. The E3 1225v3 (300MHz slower than the top i7s and E3s) is $224.99, only slightly more expensive than the i5 4570 ($199.99) which is clocked the same but lacks HyperThreading and ECC.
Your problem is in assuming that the Xeon E5s that are going into high-end workstations and servers are in any way comparable to the E3s and the consumer parts. They're not. The E5s have twice the memory bandwidth, more than twice as many PCIe lanes, and a minimum of 20% more cache (and cache sizes scale up with core count). The E5s admittedly don't have the integrated GPU, but nobody in that market misses it.
Do you know how much those GPU's cost? This isn't a $1500 home gaming machine, it's a standalone server. And spending $3-$5k on a Dell server with dual video cards is completely reasonable. Some of the Tesla cards run for $3k+, by themselves!
So in summary, you can make an equivalent performance PC for $1500-$2000 dollars.