Auto payment/registration script

[dolus]

I have quite a private community going at the moment on my vbulletin forum, it's version 3.8.7 but i want to change the registration process a bit.

Right now anyone can register, and they see limited access to the forum, but if they get vouched by existing members then they can be given full access. If they don't know anyone they can pay a small fee to get full priviledges.

Currently, it is all done manually, however, i'd like to try and get some sort of automated payment script installed for registration.

The way i'd like it to work is to allow people to register as they currently do, then when they have limited access, they can either introduce themselves by creating a thread and get vouched, or they can hit a pay now button, which will take them to a payment page, then once they've made the payment they will automatically be promoted to a higher usergroup to get full access to the forum.

Any ideas if this is possible, or if anything like it exists?