After doing more testing, I decided to go ahead and provide shared hosting for Mastodon instances.
This will be a trial but unless something goes horribly wrong, I believe that I can price it at €5/month for an instance of up to 100 users.
This can greatly diminish the cost of running small instances and remove the technical barrier from everyone who wishes to run their own Mastodon Instance.
Let me know what you think https://masto.host/#pricing-table
@eller82 DB size doesn't count towards the disk space limit.
The main usage of space for small instances is remote cache, that is cleared every week. See: https://github.com/tootsuite/mastodon/blob/master/lib/tasks/mastodon.rake#L47
But it really depends on the community, if it uploads a lot of gifs and images, it can go fast. If it uses mostly text, then it can last a long time.
Still, adding extra space is cheap.