There is an option in eCart 5 that will allow you to set up a cart without a payment gateway, however, you should never store credit card information on your database or send it through email. Doing this is not recommended because of security on your database or email and is often times illegal. Payment gateways exist because it is an expensive process to get their databases to be secure enough to store credit card information and get it certified. You would have to find a different way to get the payment through if you chose to not set up a payment gateway.