Actually, it may cost a billion dollars to retrofit that jet for presidential purposes.
The cost to retrofit the Boeing 747-8 gifted to the U.S. by Qatar for potential use as Air Force One is highly debated, with estimates ranging from under $400 million (U.S. Air Force estimate) to over $1 billion, involving extensive work to install secure communications, defense systems, and presidential infrastructure. While the aircraft itself was valued at $400 million, the conversion, including stripping it down and rebuilding it to presidential standards, adds significant cost, with some suggesting it could reach $750 million or more.