How about moving stuff _from_ the Moon back to Earth. Harvesting the Moon for rare materials is going to be relatively cheap.
The only thing that comes to mind at the surface would be Titanium but even there the economics would probably not make sense if your goal is to use the material on Earth.
Every material is rare outside of gravity wells. Even plain steel, aluminium or magnesium cost >$1000/kg if you want them delivered to geostationary orbit. So this material would not be for earthbased construction, it would be for space factories, space-based solar microwave powerplants, spaceships etc.