Others noted this should be $19m, not billion. That said, often a more useful analysis is percent of GDP -- this can give a sense of what fraction of effort of the total economy went into it. On those terms, 1943 GDP: $200bn, 2025 GDP: $30tn, for an increase of 150x.

So, depending on how you count, these were $19-150m each in today's dollars, or between 1/10 and 1/3 of an ASML EUV machine.

1 mil seems like an arbitrary or at least rounded number, and also it's not like you could get one on the market, so maybe it actually didn't cost a million

For comparison, the unit cost of Boeing B-29 Superfortress (manufactured 1943–1946) was $639,188. In total 3,970 B-29s were build.

https://en.wikipedia.org/wiki/B-29

No, inflation it's $19,476,300 in today's dollars. 19 million not billion.

You're an order of magnitude off: $1M in 1943 is ~$19.5M today.

https://www.bls.gov/data/inflation_calculator.htm