As the story goes, they were ready to cut the number of band-aids in the Apollo first-aid kits in half to save weight. Of course, that was for the LM, which is a totally different beast than the launch vehicle.
Perhaps this goes without saying (because no one has said it yet, but I will), but we still have at least one LM: the leftover from Apollo 18. The makers of From the Earth to the Moon reportedly refurbished it to use as scenery.
The LM at the Smithsonian is actually the second one built, according to Encyclopedia Astronautica. NASA decided not to test fly it, and went ahead with the Apollo 9 flight of LM-3 (“Spider”). It further says that LM-14, intended for Apollo 20, was still under construction when that mission was cancelled. Not clear what happened to it. And what happened to Apollo 19’s LM-13?
As for CSMs, the last one apparently was the one that docked with the Soyuz in 1975. It was nearly pressed into service as a rescue ship for the second Skylab crew. It was also almost used to fly a booster up to Skylab to keep it in orbit until the shuttle was ready.