WordPress/BuddyPress plugin to allow users to create members-only posts [closed]

Question

I'm setting up a site using BuddyPress and I'd like to be able to give members the option to create new blog posts that are viewable only to members of the blog itself. I've found a couple of plugins (s2member, for example http://buddypress.org/community/groups/s2member/home/ ) that seem to do a great job of allowing the admin to restrict posts and content behind a paywall, but nothing that really seems to add anything into the Post Edit screen that's simple for an end user to interact with.

Basically, I'm looking for something that adds a "Members only" radio button option to the Visibility selector in the Publish meta box. I've checked the BuddyPress plugin repo and the WordPress one as well, but haven't really found anything. I'm almost ready to roll my own, but didn't want to re-invent the wheel. Anyone know of anything, or should I get coding?

Oh, one other option: is this built into WP or BP and I'm just being really, really stupid?