We pay 20 EUR per month for the Host Europe Linux Server Advanced 8.2 package, plus a few Euros a year for the domains, and that’s all. That server contains the edgeryders.eu website and about 10 other, smaller websites. The Discourse package prices are for “managed instances”, where you don’t have to care for setting up and updating the Discourse software.
In your case, if you want to self-host Discourse and not spend much effort on setup etc., a Docker based host like Digital Ocean seems a good idea. Because DIscourse is supplied as ready-to-install Docker images officially, while installing it yourself on a vanilla Linux system is possible but took us some time to figure out. Expect ~40 EUR/month for hosting with Digital Ocean.
We did not yet decide how we want to offer this service as a product. For small hosted communities like your forum, this does not require us to get a larger hosting package. So I would imagine that we only charge an initial fee for the whitelabelling setup and a per-hour rate in case any support / development / installation work is requested by the hosted community during the hosting. Plus some fee for community management services if you want us to provide that as well.
It’s available for your use in a whitelabelling setup, yes. Again, not sure if and how we want to charge for this, but be aware that it’s not yet a polished product that we can offer to clients more broadly. So if you are ready to play early adopter here, I guess this would help us as well to finish this part of our software setup more.