Nick

When you say one post, do you mean something like a blog post for that listing or logging in and creating a new “post” / listing?

In the design I’m working on, I want the paid listing to be able to make an announcement. A free listing would not have this option.

My idea is to have a Text-area field only available for the paid listing. Then they can log-in and update the listing with a new “post” / announcement in the Text-area, replacing the old text that was there before.

Would that work for you?