Let’s look at ebay.co.uk (the website, not the company). As of October 2017, a workstation with two Xeons can easily be found for under a Threadripper. What’s needed? Lots of RAM, multiple CPUs, some PCIE slots. Some drive slots. More than 1 network socket, to isolate experiments.
Loose thoughts: Dell T630 seems to have lots of disk space, lots of PCIE, should be quiet… but, after a bit of search, it’s also loud when multiple GPUs are inserted. I could try to quiet it down replacing fans, but that’s a bit too much hackery for what I want to build. For the same reason, a rack server is not being sought.
Adventure #1, amazing deal. I thought I won the ebay auction, seller sadly has sold elsewhere. As in, on gumtree. “Normal” people sometimes buy workstations and sometimes sell just to get rid of them.
So, ebay/gumtree/…. Browse often, browse regularly. There are deals that will show up. Write the components down, price them to asses the worth of the setup, don’t overspend.
Adventure #2, good (not stellar) deal. I’ve “bought now”, seller doesn’t write any messages AT ALL, but their paypal (I am fond of buyer protection) email address, which is googlable, which leads to his blog, and there is a phone number. Which, upon texting, responds with “computer sold elsewhere”. Disappointment.
An option is to pick a dual motherboard, buy RAM and ES/EQ CPUs, if one is willing to risk. As in, ES/QS (Engineering Samples) will be similar to models known from ark.intel.com, but not the real thing. They will, most probably, offer a better power for money. Also, browsing a lot, there are chips not present in Intel’s library, thanks to cloud providers, who get them customised. But this means a PSU, fans, making it quiet, and a workstation motherboard that might have a very different set of connectors to what consumer grade purchaser is used (why would you NOT need a 5.1 sound card in a workstation?).
Adventure #3, decent computer, bidding 2/3 of total value, just in case. Few hours later, got a “2nd chance offer”, which means the winner resigned and I can follow through. This is when pricing and bidding conservatively has helped. Also, I now have a desktop, still under warranty.