Comment by walrus01

re: your last paragraph, there's probably only about 30 to 40 (at max) reputable relatively high volume dealers of used/refurb ex datacenter server equipment dealers on ebay that are located in the US48 states. It would be very risky in my opinion to buy a used GPU or multiples of GPU from some rando who has 14 feedback.

If you search ebay for server equipment like a Dell R840 with 768GB RAM, the same sort of dealers who are selling that and have thousands of feedback (at 98.5% of greater rating) are the ones I would consider much less risk.