The Mercury, Gemini and Apollo programs cost about $25 billion, and that was in 1960's dollars. For all that money, and a decade of work, we got a few hundred pounds of moon rocks and dust. However, as a direct result of the research and development done to allow those journeys, we transformed the modern world in ways never imagined, to include GPS, improved satellite and land-based communications and many new materials which are in daily use today, not to mention the revolution in computing power and electronics caused by the need to miniaturize electronic instrumentation and computers on board the ships. The total value of the spin-off technologies of our earlier endeavors in space is likely in the tens, if not hundreds of trillions of dollars, a pretty good ROI in anyone's estimation ...