Custom Registration Page with Payment Gateway at End of Process


I am using an addon for Gravity Forms with BuddyPress – – Is there a way in which I can complete the sign-up process with this addon and then direct the user to the payment page? I have the ability to redirect the user to a custom page. What information will I need to be passing and to what page/action? Or is it possible to display the custom form and have the payment options displayed after completion as normal?

Thank you