For media hosting, you can go an incredibly long way without needing to dip into “server grade” hardware.

An old desktop with a GPU and plenty of storage will be just fine, especially if you are only serving a few clients.

ECC isnt really that important, you’ll likely never notice if you get a memory error.

The one major advantage desktop PC hardware has is power usage and noise. They are generally quiet and reasonably power efficient, which matters a lot.

My advice would be to start small on an old desktop, and then upgrade when you actually hit a limitation of your current hardware.