"Materials on the Moon's surface contain helium-3 at concentrations estimated between 1.4 and 15 parts per billion (ppb) in sunlit areas,[1][61][62] and may contain concentrations as much as 50 ppb in permanently shadowed regions.[63] For comparison, helium-3 in the Earth's atmosphere occurs at 7.2 parts per trillion (ppt)."
Stretching the use of the word copious here... Helium 3 is specifically what I was thinking of when I said "the only exceptions would still be so rare as to require gigantic energy inputs."... Also, utilizing it would require fusion technology we don't have yet.
Listen, going to the moon and space travel is neat and all... There's just no way space mining makes money with current tech.