Great for you with all the work you do with it. Not so great for me with my much lesser numbers of tanks being inspected. The fact that it is relatively cheap for you does not mean it could not and should not be cheaper.
I am PSI certified, and I am current with that certification. I think training is important, but I also think that the training is overpriced. As a consequence, because there is no real legal requirement that people receive such training, a lot of shops will balk at spending that kind of money to get their employees properly trained for something they think they can do themselves. How many shops slap stickers with their own shop's name on them or with no identifier at all? How were the employees who did those inspections trained? I bet that if the cost of continued certification were less, more shops would be willing to have their employees get that training, and PSI might fill more classes and make more money.
The summer 2014 issue of Alert Diver includes the story of an O2 deco bottle explosion that occurred just after its owner, who nearly died, had had the tank O2 cleaned and inspected. The analysis of the tank remains showed lots of silicone. The resulting investigation showed that the employee who did the O2 cleaning and inspection had had no official training and had no real clue what he was doing.
If another agency wants to offer competent training at a more competitive cost, I have no problem with it. Maybe we'll all be a little safer.