It may be like the sand paintings of the Navajo. They make them for sale to tourists, but put a small “error” in the design that makes them “non religious” items.
Indeed it is the masks that are sacred. The Kachina dolls are mostly instructional. But that being said, old Kachinas are looked at much like old and valuable books about religion, and using them for commercial purposes is seen as in bad taste.
Some years ago, a Phoenix cartoonist did a series using Jesus in the same way as Kachinas were used in advertisements, to show how tacky it looked. It did.