Not really. The SR-71 was the final plane of an extended program called OXCART which created the A-12. The program was nominally to replace the U2, but even oxcart was within a large aircraft design plan. There was even a interceptor (YF-12) that was meant for shooting down Valkyrie-class mach3+ bombers. These aircraft were very similar to the 71, so similar that most people seeing them might not spot any difference. Any assessment of the 71's development costs is therefore very difficult.
"YF-12C: Fictitious designation for an SR-71 provided to NASA for flight testing. The YF-12 designation was used to keep SR-71 information out of the public domain."
Not really. The SR-71 was the final plane of an extended program called OXCART which created the A-12. The program was nominally to replace the U2, but even oxcart was within a large aircraft design plan. There was even a interceptor (YF-12) that was meant for shooting down Valkyrie-class mach3+ bombers. These aircraft were very similar to the 71, so similar that most people seeing them might not spot any difference. Any assessment of the 71's development costs is therefore very difficult.
https://en.wikipedia.org/wiki/Lockheed_YF-12 https://en.wikipedia.org/wiki/Lockheed_A-12
"YF-12C: Fictitious designation for an SR-71 provided to NASA for flight testing. The YF-12 designation was used to keep SR-71 information out of the public domain."