A friend and I mined with 30x 1080 Ti's and 30x RX570 last time, but sold most working off eventually, and the ones that was broken I got refund for through RMA. It was fun and all, but it took a lot of work and time for maintenance, so I wouldn't recommend anyone doing that again.

I did just buy two of his remaining 1080 Ti's for $350 each, which I think is a fair price. I also bought an RTX 3080 back in November ($950) and it has soon paid for itself. I bought the RTX 3080 for myself and gaming, so the mining on that is just an added bonus.

Also good to warm up two different rooms now that it's cold.