Seems like you’re looking for something I had made myself some months ago:
I’ll avoid repeating that build log so I’m linking you to it.
As of now it has been rock solid, gigabit transfers over the network are a walk in the park for this machine, should be using the least amount of power possible for what it is (still didn’t take any power readings).
One thing I don’t suggest you to go for is the case. Get a proper case for an mATX board if you got the space.
I bought the SSDs on the last black friday at 200$ each. I think the total came up to ~1600$, without the boot SSD I already had.