I bought a bundle with 512GB of RAM and an older 24-core EPYC (7F72) + supermicro motherboard on ebay a bit over a year ago, it was really an amazing deal and has made for a truly nice NAS. If you're okay with stuff that's old enough that you can buy decommissioned server stuff, you can get really high-quality gear at surprisingly low prices.

Companies decommission hardware on a schedule after all, not when it stops working.

EDIT: Though looking for similar deals now, I can only find ones up to 128GB RAM and they're near twice the price I paid. I got 7F72 + motherboard + 512GB DDR4 for $1488 (uh, I swear that's what I paid, $1488.03. Didn't notice the 1488 before.) The closest I can find now is 7F72 + motherboard + 128GB DDR4 for over $2500. That's awful