Discourse is open-source, there's no fee:) That $99 is for them to install it if you're too incompetent to do it yourself (lol)

We rejected Discourse because the cost of marrying it to our design, as well as adding in the custom functionality we need (both what we've done already and what we'll need to do in the future when we build out MoneroID and MoneroTrust), would well exceed what we've spent on the forum.

I do encourage crowd-funding for specific forum improvements and features, as we can tune the forum to work the way we want.