anything on this?
The way that you can achieve this is by setting up a Free Membership Signup Form or WebForm. (Keep in mind you do not have to advertise this as a Free Membership) Then also create a push notification that will email you when a new member signs up for that membership level. At that point, you will be able to review their account. If you would like to approve them, you can move them to a different membership level or email them a purchase link.
Thank you for this suggestion! This feature request or some aspect of the functionality suggested is currently being reviewed for possible inclusion in a future update. In the meantime, the best approach to currently getting this done in MM is outlined above.
If there is additional information, this post will be updated to reflect it.