Hi @sabcoopers,
wpForo is a free plugin. This is wpForo plugin page not the addons. Addons are extensions.
As you may know there are dozens of WordPress forum plugins and no one of them has private message feature. So please don’t say this is a must feature for forums. Private messaging is more likely Social Community feature rather than forum feature. You should install profile builder plugin for that. wpForo is a forum and it has a full package of features to create an advanced discussion board and we work hard every day adding new features in this forum for free.
If you want a private discussion, please note, wpForo has all functions to create private topics (free, in core), also there are options to create private forums. These are the forum must features. So the wpForo already has many options to allow users discuss privately without addons.
This forum plugin has almost everything to build a professional discussion board in just a few minutes and for free. Please review this plugin as is, this is the wpForo plugin review section, this is not a place reviewing addons or addon prices. Addons are separate, optional plugins, they are not wpForo core parts.
In any case if you need some of those addons and they are expensive for you we’re always ready to discount any addon. Just contact us if you need.