Spree now includes integrated Authorize.net support. Spree can be used with any of the major gateways supported by the excellent activemerchant plugin. Spree currently only supports a couple of these gateways “out of the box” but the rest can easily be added by writing a simple migration so that the gateway settings can be configured through Spree’s admin interface.
Ricardo S. Yasuda (shadow11) wrote just such a patch for Authorize.net so now you can just select it as your gateway and configure your login API information. Its really quite simple to add support for your gateway. If you don’t believe us, just take a look at the initial commit for used to support Authorize.net.
So once you get your preferred gateway working with Spree, please share your patch with the rest of the community.