It'd be interesting to see who authorized the sales, since no one owns the moon...In particular, there are two international agreements, written under U.N. auspices, that are relevant to the question of owning territory or resources on celestial bodies such as the moon, the asteroids, and the planets. These are the Outer Space Treaty of 1967 and the Moon Treaty of 1979.
The Outer Space Treaty, which has been ratified by over 50 nations, including the United States, prohibits any claim of national sovereignty on an extraterrestrial body. The treaty makes no mention of private property, but it undercuts the ability of any government to recognize or enforce a private claim. Negotiated at the height of the U.S.-Soviet space race, the pact was a creation of Cold War politics; it assuaged each superpower's fear that the other might claim the moon or place nuclear missiles there. (The treaty bans military bases, weapons testing, and military maneuvers on celestial bodies.) The economic potential of space--the first commercial satellites had just been deployed in the mid-1960s--was a secondary consideration at most.
The Moon Treaty, too, reflects the international political climate of its era, in this case the 1970s emphasis on wealth transfer from the West to the Third World. The treaty (which applies to all celestial bodies, not just the moon) prohibits the ownership of territory by any government, "non-governmental entity," or "natural person"; space resources are defined as "the common heritage of mankind" and placed under the governance of an ill-defined "international regime."
The Moon Treaty, however, was not ratified by the United States, and it has dubious international standing; its signatories include Austria, Pakistan, and a half dozen other nations, none of them major space powers. Nonetheless, the treaty is nominally in force and could serve as a precedent for future attempts to collectivize the solar system.