To prevent the registration from sending an email, you send send_email=Falsea call RegistrationManager.create_inactive_userin your submission to register the user. After creating the user, you probably want to create a landing page using the PayPal buttons for payment. Ask the user to click the payment button to pay. Usually I send user.idin the field customfor the payment button.
django-paypal IPN, user.id custom IPN. , , , , .