Got it taken care of:

Redirect to "PayPalSubscription.aspx" and send it the RoleID of the role that the user wants to subscribe to and the rest works by itself.

CJ

The general 'flow' is:

1. Button that text changes dynamically depending on what role the user is in.  The text is determined in Page_Load
2. If Not IsInRole("Registered Users") and Not IsInRole("Subscribers") Then button1.text = "Click here to Register and Subscribe", etc. etc.
3. Also in each 'If' statement is a different handler for the particular button need:  If they need to register and subscribe, it goes to a sub which displays text boxes to collect the user data and then creates the user account (registers them).  Once the user account is created (registered), it automatically calls the PayPalSubscription.aspx and sends the RoleId of 'subscribers' and works its magic for creating the paypal URL, handling IPN, etc. 
4. Once the user is returned back to the main page (or whatever page you assign for 'returnurl'), the user is registered, subscribed, and logged in.

My basic goal was to make it as simple as possible for people to register and subscribe by going through as little user interaction as possible.

It's really pretty simple once you get into it.  DNN has all the core work there, it's just a matter of accessing it in a more 'user friendly' way.

CJ