Adding onto this, it's fairly cheap and easy to host a Lemmy instance if you have any amount of experience with using a VPS.

A friend of mine is hosting her instance for a group of friends on a $5/month Linode instance. From what we see of the stats it should be able to scale up to many times more users and activity than what it has now, and that's based on the current state of the Lemmy codebase. There are additional performance optimizations being worked on that will help reduce those loads, and thus costs, even further