The reason why EVA are not selling Kitty amenities and are patrolling against stealing on board is because these items are copyright protected, and a Japanese firm own the copyright. EVA have to pay the license fee to use the Kitty image on any of their products, so the supply is limited. It is not like EVA can order as many as they want for the public demand. Since the Kitty is such a big success for EVA, I can image the Japanese firm raised their license fee quite a bit year after year.