If you can process the credit cards via phone then
Mal's e-commerce with Mal's ecommerce might be the answer for you. You can make it so they submit their info including the CC number and the site will capture it. You log in to your account and retrieve it and process it at your business. No merchant accounts needed and it is free up to a certain point. I have a client who has used it for 7 years now without a hitch and she has some large companies that buy from her every month.
Good luck!