I got 48 vCPUs and 96GB DDR3 for <$300 in 2016 off eBay. It isn't the most powerful, but it was cheap.
Together with a full standing rack on wheels, I bought them for $600 cash (plus U-Haul rental to get it home).
My trick is craigslist in a city with datacenters (PHX). There are resellers here who buy used hardware from local datacenters and resell them to smaller businesses. I've had it running 24x7 for almost 3 years now and it is still going strong.
https://www.reddit.com/r/homelab/ has some good references for acquiring hardware for a home lab setup.
The closest I can get a disposed server with those specs is at least 8k
At least that was the case when I set up my home server rack ~2 years ago. (Though 24TB might be too much since server grade SAS storage is very expensive even when it's used. So what I did was to buy servers with as little storage as possible and then just put SATA HDDs that I can get for dirt cheap.)