Hi Simon,
I’m searching for the same tool, and if I can’t find it, I will make one myself. It should be a useful plugin.
The process should be well thought and streamlined for the user (client)
I’m thinking of restricting posts based on their category, making one or more categories a members only zone and having an alternative teaser so unregistered users would be encouraged to register (and pay)
An important feature would be the cancellation of the monthly subscription – when a user stops paying he should be blocked from the members only area but not deleted from the wordpress database.
In my specific situation, I will open to the general public posts and comments from the members only area after a certain time has passed, I will experiment with it, starting with two week delay. This is because of the nature of my subject – stock and option trading. It will be interesting to see what members did a couple of weeks ago and if they are having consistent profits with the education they receive.
I find it hard to believe this plugin is not out there.
It shouldn’t be too hard to make it if you know how paypal works and some PHP.
I’m currently learning those subjects.