My home server is mainly a file server and automated backup server. I also use it to host dedicated servers for some games my friends and I play (minecraft, KSP dark multiplayer, halo ce, etc.). It does PiHole and steam/origin/blizzard/uplay download caching (steam game install from a bonded dual-10G server is fun) as well.
I picked up a SuperMicro mini-ITX 8 core Xeon-D based server board on eBay for ~$400. The idle power is <10W and it runs off 12V DC and has dual 10G ethernet, 6 SATA ports, IPMI, A x16 PCIe slot, and an x4 M.2 slot.
With 6x 10 TB WD Red drives and 2 NVMe disks it pulls about 25W at idle (mostly the drives). If I wanted to run the Kodi or Plex on demand video transcoding I'd probably throw a used quadro in there (or, hack around the transcode limit on a GeForce card).