The cost of an F-35 airframe (no engine) is rising since last year at this time.
Back then, low-rate initial production batch 4 (LRIP-4) shows a lower cost than this latest contract for LRIP-5 aircraft.
Roll away cost of each F-35 for LRIP-4:
Roll-away cost of each F-35 for LRIP-5:
(rounding to nearest decimal point)
Last year, engine prices ranged from $19M each for the F-35A variant and $38M each for the STOVL variant.
Granted that a lower number of aircraft are ordered in LRIP-5. The assumptions of the program are that each successive batch would be in bigger quantity and thus cheaper. The problem; is a lack of stability in the aircraft design and thus: low production learning curve.
In the overly optimistic days, LRIP-5 would have been 120 aircraft.
With LRIP-4 being "peak-production" thus far (no one can say when full-rate production will happen) any assumption of the F-35 being "affordable" is officially nonsense.
A recent DOD internal report as well as recent comments from the DOD F-35 program manager show more negative outlook for the program.