Arizona now has the Boating Safety Course On-Line. Taking the Course is free, but the test and Certificate is $20.00.
While I recommend attending the physical class, this is better than nothing, and it meets the requirements for any State's mandatory education laws.
One note, if you're required to attend a Boating Safety Class by Court Order, based on a violation, this probably won't qualify. Most Courts require physical attendance at a class.
http://www.boat-ed.com/az/az_internet.htm