How much would a launch pad that will be used four times normally cost for what they're planning to launch? Without knowing that I can't say if they overpaid 10x, 2x, got it exactly right or got an amazing bargain.
In 1965, the Vertical Assembly Building, which was at that time the largest enclosed volume in the world, cost $117M (on a $23.5M original construction contract). That would be about a billion dollars in 2020, but it was completed in 3 years and was used to stack 13 Saturn Vs. It was later used for the 100+ Shuttle missions as well, but there were additional costs to modify the building for this purpose. The VAB is still planned for use for future missions.
I picked the VAB because it's current dollar cost was roughly a billion dollars.
Total cost for constructing Launch Complex 39, which includes the VAB and the crawler-transporter launchers was estimated 1t $500M in 1962 for 2 pads. A total of 153 launches have occurred from LC-39. This number is greater than 4.
https://www.popsci.com/blog-network/vintage-space/nasas-vab-...