C-5 Galaxy Minuteman ICBM Drop Test
Compared to some of the stuff the US Military did during the cold war, this one isn't too bad, it probably didn't cost more than a few million dollars. The Aviationist has the story:
In 1974, the U.S. thought that the best way to preserve its ICBMs (Inter Continental Ballistic Missiles) from Soviet nuclear strikes was to load them in C-5 Galaxy airlifters and keep them on the move.Via Quora
A three-stage Minuteman, 56 feet in length and 86,000 pounds in weight, was attached to some parachutes that could drag it out of the cargo hold and then point it upward, then it was loaded into a Galaxy and air launched over the Pacific from the aircraft: a timer ignited the rocket motor and the missile flew for about 25 seconds before it cascaded into the Pacific Ocean.