Pay to publish

I need a "pay to publish" module that work like this:

• The user makes an account and he can add some custom nodes that are NOT published by default (already implemented with CCK)
• The user has a special section called "My content" where he can see all the nodes he has created (already implemented with views)
• When he access "My content", the user can see the status of the nodes and publish the ones that are unpublished and we have 3 cases: (needs to be implemented)
1. he can buy a package that allows him to publish a certain number of nodes and after payment, the node is published an the credit is decresed by 1 (needs to be implemented)
2. he can pay only for the current node (needs to be implemented)
3. he has credits from a previous purchase and the node is published with no cost but the credit is decreased by 1 (needs to be implemented)
• The node expire after some days and it is unpublished but is still accessible to be published again from "My content" section (expiration is implemented)

The module needs to be independent of the payment gateway BUT when it's ready, it needs to work at least with paypal (the user must be able to pay with his credit card by paypal, even if he doesn't have an account with paypal)

If the module will be made, 6 months after I implement it into my website, it will be available free of charge for the drupal community.

Please leave here some realistic financial demands.

Thanks and sorry for my English and for the long post.