JRiver Id is NUC and fully configured with JRiver Media Center.
From the JRMC site:
You can use an Id as a stand-alone media computer, or as a basic HTPC, and control it with a phone. You can play to it as a DLNA Renderer, or from it as a DLNA Server. It can be a Backup Server. It’s small (about 4″ wide) and low power (about 10 watts) so you can run it 24/7. It has the audio features of JRiver Media Center. The Id 300 and above also play video. It works with JRiver’s Media Network.
New from JRiver: $315. I’m selling my unit for $200. Minor scuff marks on top, but operationally in great shape (after all it’s a NUC).