I agree $30 sounds a lot for certification, but consider the time someone has to spend to review your software, an hour is gone quick.
I'm sure after a few sales you have recovered your certification fee, and a certified product will give security to potential customers and should result in a higer turnover.
It shoiuld also weed out those hacker programmers which have no idea or don't care about good programming techniques.
I know what I'm taking about I have been design authority for some major see more IT and Software Projects