As widgeon said, the financial impact of an AD is calculated by the FAA, including parts and labor. Who pays for these 2 costs is worked out by the manufacture (with some input from the customers). Since the Koala is a new machine, they should all be under warranty.
I also think that Augusta needs to deal with this problem fairly quickly, since there's usually a large number of sales when a new model is introduced, and future sales could be hurt without an effective response.