The problem with the F-35 was that it was designed to replace everything so it is by definition a monopoly aircraft, and early on they decided that developing alternatives like two or more engines was "inefficient", but ironically by making it more efficient they have eliminated all internal competition, so there is a provider and they have no competitors or experts with internal knowledge of what they are doing and how they are doing it so you can think of a number and then triple it, and then double it again and that is the asking price. Because it is a multiple of what it actually costs you can show some flexibility and reduce it a little when they put the thumbscrews on you, but even after hours of waterboarding you still make a nice profit and that is all you really care about. If you are not making enough about half way into production or if faults are found then ask for more money to find solutions, or just say the cost of making the product to the standard needed has gone up... it is OK... no one ever checks.