Hi Peter, thanks for the link. It has taken me a while to read through the many, many pages of the link you shared. I really enjoyed the unfolding of the add-on and 'tenants' sure looks like an amazing team to work with and get support from. Sadly the add-on won't allow for 'financial control' of any sorts. So anyone joining the site can actually post in that forum, without having to pay for a listing.
I saw that Floris with Xenfans has a marketplace forum where he allows premium members to post in the marketplace forum. But I don't quite know if that's the right strategy for an actual directory. Might be a great add-on to sell a quick item here or there.