Plans and pricing generic app?

I'm in need of adding a plans and pricing schema to my website to charge a user for the use of certain feature. In this case, the User adds Notices to Points.

A User should not be able to add more Notices than his' Plan allows. Stuff like that.

A quick google round gave me nothing to look around (django pricing and plans are terrible search terms) so i was thinking in rolling my own solution but may be you know of something of interest.

I'm not very sold to the way the pricing schema would work or how to handle the pricing, but that's not in the scope of the question.