For what it’s worth, I looked around and saw “ready to run” Mastodon hosting services starting at $6 per month, not too long ago. Tempting, but the service is the easy part, maintaining the community can be much more challenging.

Smaller communities don’t get targeted for commercial exploitation. But, then, something has to support them even if they don’t cost much to run - they still cost something, both for bandwidth/storage and moderation/curation effort.