I'm having trouble finding cheaper fighters. Which one/s are you thinking of? That's not even allowing for the superiority of the F-35's capability.
Geez, it's amazing! One tries to answer a simple question, which leads to more questions and comments, which leads to more questions and comments, time to step off the hamster wheel... One can only say that an aircraft program that has been working for 15 years (more if you count the earlier development work) and is still in a development stage, odds are, it isn't going to turn out to be spectacularly good...