The F-35 isn't that expensive these days. It's still a huge amount of money to spend on something good for nothing but war, insert your view here, but the price isn't much different than the new F-16s being bought by the Israelis.

That being said however stealth aircraft are not cheap to maintain at all.

Curiously I wonder if a similar problem is occurring with SA-400 missiles and other Russian air defenses. They may be too expensive to shoot at low cost drones such as the bayaktar.