Yes—scientifically and historically they are extremely valuable, but almost none of that value can be realized in a private sale of Apollo material. NASA’s Office of Inspector General has treated stolen Apollo lunar samples as worth millions of dollars (a 2002 case involved about $21 million worth of Moon rocks), and illegal sellers have advertised prices on the order of $1,000 to $5,000 a gram.
Apollo rocks returned by NASA missions remain U.S. government property. Private citizens generally cannot lawfully buy or sell them; unauthorized possession or sale of government lunar samples is a serious federal crime. Pieces of the Moon that arrive as lunar meteorites (natural finds, not Apollo cargo) are a different category and can be owned and traded where meteorite sales are legal.
Source: NASA Office of Inspector General — Cracking the $21 Million NASA Moon Rock Caper