MP 7.1 are going down on prices very fast, but both are intel based, so, both are obsolete for future MacOS releases. Save your money for the new M2-cool variant Mac Pro.
Do show us your sources to back up your anti-Intel Mac campaign. I just checked ebay just now and found:
USA: 3.5 8 core: USD$4429
USA: 16 core 3.2: USD$6630.00
USA: 2.5 28 core 768GB RAM, 1TB SSD, 8TB NVME, RX580: USD$21,200.00
Germany: 3.2 16 core QS CPU 580X: USD$5123
Germany: 2.5 28 core 580X, 256GB SSD(??): $11,267.93
None of those are what I call "prices going down very fast", they are the same prices from the same sources on eBay I looked at when I was searching to buy the 7,1 a few months ago. No change at all. And hence why I purchased a brand new one which has worked out brilliant.
You can currently buy a factory sealed 2013 Mac Pro with D500 GPUs on eBay for $600. Not necessarily the cheapest, but might be the easiest/most reliable solution to replacing your failed GPUs if you need that Mac Pro up and running again.
Are there any D700 spec machines around? I'm tempted to get one just for the GPU (mine has D700s). I don't normally use the 6,1 but when my high-spec 5,1 failed I jumped over to the 6,1 until I could put in my order to join the evil 7,1 club.