This part is incorrect. Unless you need functionality specific to workstation & server GPUs, it can be an order of magnitude cheaper to buy a high end gaming GPU. Cryptominers normally use motherboards with 12+ PCI-E 1x-16x adapters and consumer cards: https://www.youtube.com/watch?v=B6gB7GYkkiA
The same performance/dollar math applies to anyone else who needs to do GPU processing and doesn't need:
* double-precision math
* high-bandwidth connection between the GPU and motherboard
* a setup that doesn't violate EULAs
* a warranty
In my testing with raytracers, there is around a 5-15x improvement in perf/$ with consumer cards.