So you don't want to use Google Checkout, or PayPal, or setup a regular merchant account (I currently use all 3)...the result is that you're going to be paying much higher fees with the other options including limitations (ex: Propay has higher discount fees with maximum charge amounts per transaction and per month). Don't confuse payment gateways (authorize.net) with a merchant account; they're completely different and work in conjunction with one another.