James, you can do whatever you want, but don't misrepresent the facts. A custom PC with similar render numbers on many benchmarks than your new mac pro will actually run you closer to $1,200-1,500. You could literally buy three hex-core computers for the price of that single mac pro. In terms of render power, that's a far cry from "a couple hundred dollars" difference. Yes the Pro has many bespoke custom parts. But they are more or less matched to 90% by regular high end PC components. For example nobody "needs" ECC RAM at 200% markup or Xeon-class chips at 300% markup. Regular DDR4 RAM and i7 chips are just as good, if not faster, in many cases.
You don't have to build it yourself, and you don't have to buy it from Dell or HP, who also charge a hefty markup closer to Apple's, which is where a lot of these inaccurate numbers are coming from. There are tons of mid-level workstation builders out there with great reliability and good warranties. Your justification is fine, I'm not here to tell you how to spend your money. But your comparison is simply not accurate if you understand computer hardware and benchmarks.