I'm looking for a solution for a client.  Currently our client uses Course Web and a limited databases.  

The client sells a username and password to the class on course web.  They pay, then get the username and password in their email.  Using this same system, students can also buy a discounted multipack.  They then in turn get 5 predefined username and passwords in their email that can be given to 5 people. 

We would like to eliminate CourseWeb from being the "Middle Man" by switching to Moodle. With Moodle you create the username and password before you purchase access to the courses. Does anyone have a suggestion on how to handle one person buying access in a 5 pack which can be given to 5 people.  Obviously, I can do this by hand upon request but I am looking for a suggestion for an automated system. 

I assume I'm going to have to use an enrollment key but I don't want them the same for each username.  

I have been coming up with Ideas but was looking for something easier then re-coding the Core Moodle.

Idea 1) Student purchases generated code through PayPal that turns them into Teacher(or similar role) with power to invite up to 5 email address to a single class. 
Idea 2) Reprogram elediamultikeys to generate new keys on Paypal purchase
Idea 3) Use PayPal subscription's Username and Password generator
idea 4) Develop coupon plug in that generates coupon code that can be used 5 times

Looking for any existing solution to build upon.  Thanks guys!