That's still cheaper than the current GAO estimate for the new Boeing 747-8 Air Force One replacements. The current estimate, for two, is $5.6 billion and they won't be ready until 2029. (The original cost was $3.9 billion.)
He's a quick way to tell if he's telling the truth. If what he says will either personally benefit him or will hurt others, then its a good chance its true. If what he says is something that will help others but have no benefit to him, then it is a lie.
So the cost is presumably something like 2 missiles. But don't worry, the project is already years behind schedule. The first $75 billion bought us exactly 0 operational missiles in the 15 years since the contract was awarded to the only bidder.