[Typo3] usergroup subscription - developer - sponsors

[Joe Frontman]

1) to developers:
 would you be able to code the following extension:
- usergroup subscription with a paypal payment processor
This extension should be able to grant permission to a certain usergroup 
after payment is completed. When a member cancels a subscription he 
should be "downgraded" to another usergroup.

How much money would you be asking for developing?

2) to sponsors:

Who would like to sponsor that module?
How much would you be willing to donate?
    a) - 10 Dollars
    b) - 30 Dollars
    c) - 50 Dollars

Of course, I would like to sponsor this module depending on when the 
module could be ready.
If things would get started soon, I would donate the amount of "c".