Moon rocks are really rare things, and pretty much all of the samples collected by lunar missions are in the hands of the world's governments. But there is another source, and it has coughed up this big lunar rock which will hit the auction block in New York next month.
Lunar meteorites are rocks that were blasted from the surface of the moon during one of the massive impacts that created the moon's familiar pock-marked surface. Inevitably, some of the rocks escape the moon's weak gravitational pull, and end up getting caught by the Earth's own gravity. Those that don't burn up as they enter the atmosphere, land on Earth to become lunar meteorites.
So far, a little over 100 pounds of lunar meteorites have been discovered, mostly in Antarctica or the North African desert. That's not much compared to the 842 pounds of rocks returned by the Apollo missions, but those are almost all under lock and key in NASA's vaults. Even the 10 ounces of moon rock returned by the Soviet Luna missions are off limits for civilians, so lunar meteorites are your only realistic bet if you want your own moon rock.
Dar al Gani 1058 was discovered in Libya in 1998, and is the fourth largest lunar rock of any type known to be in private hands. Chemical analysis shows that unlike the Apollo and Luna samples, DaG 1058 comes from the dark side of the moon, so it sounds like just the thing to stick on your mantlepiece while playing Pink Floyd's 1973 masterpiece. Of course, that assumes you can swing the $170,000 expected selling price.