When you have "Manual Payment" selected in Pro Sites it sort of dead ends.
When a user click "Pro Sites" in admin, they go to the nice little page
The thing is though, if the payment is set to "manual" then there is no "continue" or "upgrade" button. The prices can be clicked but there is nothing to save them. So basically manual does nothing. There should OBVIOUSLY be a button to submit the requested upgrade in the back end. This makes no since.
I haven't seen what pro sites can do because I haven't hooked pay pal up yet to see what is beyond this point.