Looking at the cost charts (post #5), I can understand the stiff cost for the twin engine P-38. Why is the P-47 so much more expensive than it's other single-engine counterparts?
The 18 cyl engine will be more expensive than a 12 cyl one, the turbo system (turbocharger, intercooler, plumbing/piping) cost money, bigger airframe will cost more than small one. The P-47, however, allows for 450-600-1000-1300 (thousand three hundred) mile combat radius, while carrying 8 HMGs and 425 rounds per each gun. All of that while making 430-450-470 mph. Or, carry up to 2 x 2000 lb bombs.
In light of that, price tag looks fair.
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It was contrary to policy at the time, but one could wonder what could be done with a Thunderbolt without a turbocharger. Like the P-38, they were designed to perform in the stratosphere, but were never equipped with a pressurized cockpit, and spent much of their service life at lower altitudes.
If the installed R-2800 is of the 2-stage version, we'd probably see the Thudrebird going to 400+ mph without water injection, ie. comparable with Corsair. The P-47 was making almost 430 mph in early B and C versions, again without water injection.
The P-47 was the 1st Allied fighter that escorted bombers at 25000 ft, 375 miles away, while being good at that, so turbo is a good thing for that job. There are intercepted German messages where Fw 190 pilots declind to attack B-17s if P-47s are spotted nearby (link). No wonder, the P-47 was 30 mph faster than Fw 190A at 25000 ft, and non-turbo P-47 would not be able to replicate that performance edge at such high altitudes. In 1943, the UK-based P-47s spent much of their life above 20000 ft.