I was just in AutoZone at lunch, looking at cables. Then looking at the motorcycle batteries, the Duralast Gold line had all of the same exact part numbers as the Big Crank at batterymart. They even had the ETX16L that I've been looking at, looks identical, same price as online.
I'm surprised at how small they are! Smaller than what they appear online, but if they do the job I'm going to give them a try. If you are looking for them, be sure to look in the motorcycle/ATV section.