Have a look through the forums at serverbuilds.net Honestly, there is no point in getting into the server game and buying new unless you are using it for a business or have a great deal of cash to burn. Plus, sticking with used tech is way better for the environment.
As I always say, have a look through https://forums.serverbuilds.net They have tons of guides on building whatever you need at whatever price point you can afford. The NAS Killer 5.0 is pretty great and I went with a second box for transcoding. Both low power and pretty cheap.