Most modern services providers also sell your data in order to give it to you free, which is not what I'm looking to do.

It doesn't really matter how they manage to afford doing it, what matters is the user experience. :)

I do think at some point in the future it could likely be free (once the ball is rolling with beneficiary rewards), but I think in this early gold rush state where people are claiming ground, there has to be a cost associated to it.

This is good point and probably enough to justify the lowest tier price. On the other hand, it has to take off first, if it is to become a real gold rush.

Adoption also comes from the general user, who aren't going to be creating forums, but instead using the forums already provided :)

This might be true. Or the price might be enough to make a potential community manager to use another service instead of chainBB.

Note that it might not be so easy to acquire STEEM if you're a fresh steemit user. And there will be many of those.

This is something else to think about - how to make the account registration and management easier to use than what is currently in steemit. We don't want only the technically savvy communities here, do we? :)

BTW, sorry for just being critical - I'm just trying to help. I love the whole thing, and huge props to you for starting it. :)