best nas for home media server remote control

So can I build a raid media server for say $500 (the price of a good capable nas)? That would be better than the nas? The nas isnt very powerful so a pretty cheap CPU would be stronger. I can send music to my Yamaha wxc-50 via DLNA. Then I'd probably need to run a virtual PC linux or windows to run a different music manager like JRiver or Emry unless. I can install Kodi/Plex from the Qnap app store. Looking at a used Qnap ts-453mini with a Celeron J3455 and 4-8gig of ram (listed by plex and reviews as a decent plex server being able to transcode several 4k movies in real time. I probably will also run something different for my music. THEN I want to run something like Kodi that has a slick looking interface for all of it and a Plex addon for movies. Plus I have TB's of music I can incorporate (the music started it all). I've decided to localize all of our home videos (many) and pictures which are scattered across various computers and USB drives. I didnt want to have a PC in the living room but what I've decided to accomplish has grown so now I'm looking at either a used PC or nas. As opposed to snagging a good performing 4k transcoding capable nas. You can skip all this long winded vomit.my question is.So can I build a fairly quiet raid media server for say $500 (the price of a good capable used nas)? I can source used stuff like case, etc.

Best nas for home media server remote control