It does include extras, but what exactly is unknown.

For one thing however,

it will include 87 full mission simulators, which is about 1/3 of all simulators intended to be built for the program (within the US). Each of those simulators costs around $1.5 million.

If I were to guess though, I would make the assumption that the $5.37B figure does include initial spares and some maintenance equipment.

To give a bit of context; LRIP-8 cost $4.7 billion, yet according to the JPO, the cost of an F-35 (airframe; not including the engine) was $94.8m for the A, $102.0m for the B and $115.7m for the C. LRIP-8 consisted of 43 aircraft; 29 A models, 10 B models and 4 C models.

Add those airframe costs up and you get $4.232 billion, leaving $468 million as a remainder for "other" equipment (roughly $10.9m extra per jet)

Furthermore, if you look back at the last few LRIPs, you'll find that in LRIP-6, there was $14m of "extras" per jet, and $11m of "extras" per jet in LRIP-7.

Now, to diverge a bit...

If we make some assumptions, like that the cost of these "extras" trend downwards due to bulk ordering, and if we assume that LRIP-9 includes $10m of "extras" per jet, then that gives us an estimate of $4.82 billion being spent on the 55 airframes themselves.

If you then also look at the ratios of what percentage an A model cost, compared to a B or a C model, we can then even make estimates of what each airframe costs. From LRIP-8, a B model cost roughly 7.6% extra and a C model cost $22% extra. With those ratios and the known number of each variant in LRIP-9, my

very rough estimate is:

$85.5 million per F-35A

$92.0 million per F-35B

$104.3 million per F-35C

Now, for flyaway cost; the engines for LRIP-8 cost: $13.2m, $32.0m, $13.3m for the A/B/C. If we assume they've only decreased in cost slightly (rounded down to the nearest million), then we get:

F-35A: $98.5m

F-35B: $124.0m

F-35C: $117.3m

For the flyaway costs for LRIP-9 aircraft, with engines. I'm not putting too much faith into my assumptions and those numbers, but I will point out that my assumptions have edged on the side of pessimism, assuming that the airframes make up a larger percentage of the total production lot cost than they did in LRIP 6/7/8, and assuming that the engines have only decreased in cost by 0% to 2.3%. I'm also assuming that the $5.37 billion (which is a "not to exceed" cost), is the actual cost of LRIP-9; though in all realism it'll be very close to that figure.