* Pay $15/month for a VPS (whatbox in my case).
* whatbox has a notion of first class apps, including Plex. Click a button in their GUI to install it.
* drag and drop your music using whatbox's GUI file browser
That's it.
Getting that down to $5-10 would be worth it for most who aren't into the social aspect of music services.
People claim to want it, but they put a very low monetary value on it. No new business can survive on $3 a month subscriptions.
~35 - 36 USD a year? Depends on what's going on and the volume. Probably no support or paid per incident support.
No one wanting to self-stream will pay that, so then you would need to look for investment to stay alive until you have scale.
The completely different order of magnitude endpoint I was thinking of is much more like the sort of 'streamed remote file storage as a service' (using off the shelf tech and software with a tiny bit of maybe custom glue) and almost zero support; with you get what you pay for levels of congestion and peek usage pains as potential problems to complain to that greedy last mile ISP you were forced to use because it was cable or barely better than dialup DSL.