Just wanted to add I need something similar..

 

My scenarios works like this:

 

The site is free but has some Subscriber areas (like here). Works great now.

 

I want to add a plan that gives a subscription role and a promotional item (DVD or CD) so I need certain plans to insure a good address to ship to.

 

I don't care if it's in the userprofile it can just be some free form fields the user gets prompted for.