Sadly, the "price" on the top tier ninjas in great tree was increased when they added additional, relevant top tier ninjas. Before it was just one viable ninja and two that were...not as useful. Now that we have two good meta ninjas and a third that is relatively hard to get fragments for, the devs increased the price to compensate. However, I know many people dislike this spread and would rather just have access to a single ninja, so we can send this in to the devs again.