I realized I didn't answer the CPU question, as a very quickly chosen example from eBay, there's a Dell R740XD with two Xeon Gold 6254 CPUs, 768GB RAM for sale for something like $5799 USD right now. I'm sure if I put some more time into it I could piece together something with a full terabyte for around the same price. Or faster/better CPUs, more core count CPUs by buying the system with no RAM, or minimal RAM (64GB) and then adding the DIMM kits from the more reputable refurb server part vendors on ebay.

It won't be fast at all, for certain, but it'll have enough memory to prove a configuration and be able to really use gargantuan GGUF format LLMs in the latest compiled llama-server. Re: electricity, I pay the equivalent of $0.07 ro $0.09 USD per kWh so it's not an extreme burden to have a theoretical 500W server running. Something like $35 to $50 of electricity a month if it's 500W 24x7.