I don't see much of a benefit of an on-line coach provided you 1) have a minimum amount of self-motivation and 2) can read. The internet and tri books offer numerous training schedules. Just start reading, take notes and develop a program that fits your goals. The program you come up with will only be a slight variation on something that is already in print.
When it comes to a coach who can actually see you train/race, that's a different story. The value of an expert who can analyze your form and provide quality feedback on training tactics cannot be overestimated. I haven't been able to find a non-virtual tri coach--most coaches concentrate on one discipline. My swim coach has been great but he doesn't bike or run so I am still searching for the guy who can help me put it all together.