The orbiters or "Shuttles" as they became, to bring materials to an international space station, were first proposed as a fleet for NASA and a fleet for the military at Vandenberg, CA. There was a fight to keep them civilian, whether economics had a role I don't recall. As it was, the military have been on-board almost all space flights and civilian astronaut Sharon Christa Corrigan McAuliffe place on the crew of Challenger was seen as a that finally becoming more a symbol of the peaceful use of space and NASA's commitment to education. Years before (and after Apollo 17, 11th and last Moon landing) "The Apollo-Soyuz Test Project was the first joint flight of the U.S. and Soviet space programs. The mission took place in July 1975. For the United States of America, it was the last Apollo flight, as well as the last manned space launch until the flight of the first Space Shuttle in April 1981. For the Soviet Union it was the last manned space flight until Soyuz 21 in June 1976." (Wikipedia) We just bought two Soyuz capsules.