One JPL-related source [1] indicates that the second copy can generally be obtained for 15% of the price of the first one. The primary source is "Interview with

One JPL-related source [1] indicates that the second copy can generally be obtained for 15% of the price of the first one. The primary source is "Interview with Gentry Lee, Jet Propulsion Laboratory, June 1, 1984." I doubt things have changed very much since. [1] https://history.nasa.gov/computers/Ch6-3.html https://history.nasa.gov/computers/Ch6-3.html