Am I able to Self-Host this by myself for free?
What do you want to self host?
Discourse ? If so, yes, all you need is a linux server to run a discourse instance.
You don’t have to pay anything to Discourse since its open source.
As long as you have an internet-accessible host you can host it by following the guide https://github.com/discourse/discourse/blob/master/docs/INSTALL.md
If you want to take the hassle out of setup, there’s a $100 option as well.