Best way to have login, manual payment, and customized form?

I have a client who wants to sell a service where the customers have to fill out a long form. They do not buy a product, but they are purchasing advice from the form they fill out. I have re-searched formidable forms which allows for this through pay-pal payment, but he is interested in manual credit card payment. So I would need a membership area that would allow for purchasing the product, then re-directs them to the form. Or is there a better way to do this?