I used the cpu/motherboard/ram/psu from a desktop I’d since upgraded, slapped it into a 4u rackmount case I got cheap on Ebay (it looks awful - I think it was previously used in a lab - but it’s solid af), bought a nice big cooler and some noctua fans so it’d run quiet, added an HBA card, 4x shucked 14tb drives and a coupla 1tb m.2s, slapped Unraid on it, and was up and running with an awesome nas for really not that much money. Totally worth it, that thing is awesome.

I will admit it doesn’t look as swanky as a synology, but it was far cheaper, is a lot more capable of non-nas stuff, and every part is standard and upgradeable.