Following some great advice from Tim, I have moved forward leaps.
I am however, still very stuck for a simple solution for signing up users in a simple way.
At the moment, the process of registering first, confirm with email link, find out you can't do anything with blog until you upgrade, have to find an upgrade link, click to get the upgrade options, choose an option, pay, return to site, all seem way to complicated and difficult.
I am beginning to wonder of pro sites cannot actually do what I need without serious modification. Are there any plugins that can handle recurring payments as below.
This is what I want -
1- Un-registered user likes the site and wants a shop of their own.
2- There is a menu link to 'get a shop of your own' which directs to a page of options, (this could be the pro site page).
3- User chooses option and pays, checks out and returns to their fully functioning blog
It seem that this is the process employed on almost all other sites I sign up to but I can't Pro sites and Marketpress to work this 'simple' way.
I am beginning to think using the Pro Sites plugin is the problem.
Are there any simple solutions that will handle the registration of new users and blogs in this way?