This would create a two tiered social commons however. Someone like me, homeless and on disability, what could I afford? Where would my word be heard?

It could also create "free" platforms, funded by billionaires, to control the speech on the platform.

The answer is a communal, government owned social media platform, that mimics the rules of the town square. in the US, this includes the same 1st amendment rights. This would allow equal access to everyone's voice.

IMHO, social media should not exists at all. It is too huge and too fast for our tiny brains.