Selling leads system (sell contact info)

[DarkDraco07]

I am trying to setup a system where 2 types of people (buyer and seller) are involved for a transaction. Here is an example:

PersonA is a buyer and PersonB is a supplier. PersonA fills out an inquiry form stating what they want/need. That inquiry is posted into a forum. PersonB looks around the forum and spots the deal and wants to accept it. In the thread there will be a "purchase lead" button or something similar set to a certain price, in this case 30$. They go through a payment system (preferably paypal/paypal CC) and purchase the lead. After the payment, PersonB recieves an email stating PersonA's contact info (address, phone, email, etc...) which are set as private custom fields which were set by PersonA at registration.

I current have the Forms Hack installed for the order form part of this, all i need is some sort of payment method system that is automatic.

If anyone can let me know how difficult this would be or if there is a similar hack i can add onto what i have done so far please let me know.