Building a home media server on a budget

Hi

I figured before I start venturing into other forums dedicated to this sort of thing, I'd ask here on Tildes since I'm at least comfortable with the community and how helpful they can be here.

I'm tired of all of the subscription services I have, movies and TV shows disappearing from them, buying a film on Prime and only being able to watch it offline through a specific app. Even then, half the time we're watching comfort TV shows that we have on DVD already (X-Files and Friends for instance).

So I figured that building a home media server would give me the chance to cut the cord with a couple of these services and allow us to start using and controlling our own data again.

I have a budget of around £300 (I could perhaps push to £400 if needed) and I'm honestly not sure at all where to start. I have knowledge on how to build brand new, medium to high end gaming PCs as I've done it since I was in my late teens and built my first PC with the wages from my very first job but building a budget minded PC for use as a home media server goes completely over my head.

I've noticed that a lot of the pre-built NAS or media server boxes are very expensive so my first thought was to buy a refurbed workstation or small form factor PC that has enough "oomph" to do the trick but I don't know what ones to even start looking at and then I start to feel a little bit out of my comfort zone.

Things like getting the right CPU in these refurbed machines that offers the features I'm looking for like hardware transcoding etc., integrated GPU's, ensuring there's enough SATA ports for multiple hard drives and an SSD for a boot drive, and then to top it all off ensuring that while achieving these features the thing shouldn't draw too much power when idling as it'll be on for long stretches of time, if not left on 24/7.

I've also got no knowledge of Linux, I've never even looked at it but if it's genuinely easy enough (for someone with next to no Linux experience) then I'd be happy to give it a shot if it offers better performance compared to using Windows 10 or something.

All the server will be used for is watching TV shows, perhaps the odd film, listening to a bit of music perhaps and the odd podcast now and again. Simultaneous streaming will be fairly minimal, perhaps 2 streams as me or my partner watch one thing and our daughter watches another on her tablet. In regards to streaming outside the house that will also be almost non-existent, perhaps, again our daughter watching a kids TV show like Pokemon or Fireman Sam on her tablet when we're out but me and my partner don't tend to watch anything when we're outside the house, certainly not TV shows or movies anyway.

Redundancy isn't something I'm too horrendously worried about, I wouldn't be storing anything like photos that we wouldn't want to lose on it and while it'd be annoying, losing a drive with TV shows or films on it wouldn't be the end of the world.

Any help would be massively appreciated, thanks.