Internet4associations supports Authorize.net as a gateway. If you're already configured for them, it's as simple as entering your Login ID and Transaction Key and you're off to the races.
With Authorize.net members and contacts can save a credit card "on file." That information is not actually stored in your database but it functions that way. It can be used to pay for registrations, renewals, product sales.
We also support eCheck, this is essentially ACH. Instead of the member entering credit card information they enter their checking account number and routing number. If they do this you save on the percentage that would otherwise be paid to the credit card company.
Finally, if a member has stored payment information on file and if they agree, we can automatically collect dues at renewal time on your behalf and deposit the funds in your account. All eCommerce is directly deposited to your account.