Authorize.net, basically just an API front for the real money handling, is only available through 3rd-party resellers. My best guess is that 37s's bank is one of those and is also providing the merchant account.

I know that you can just grab a merchant account and then find a reseller for Authorize separately, but it just seems easier to take the package deal from someone, and banks are safer than some random Authorize reseller on the web, IMO.

No. There's a misconception that money is immediately deposited into your merchant account once a transaction is authorized and captured.

In fact, there's a middle man called the merchant service provider which holds your funds and deposits them to your merchant account. They are contracted out by your bank.

A transaction is sent through Authorize.net to the msp then through to the customer's bank.