I became interested in purchasing a piece of the moon for my collection of curiosities. Turns out, moon rocks are pretty hard to come by. NASA owns em. But, it also turns out: a whole bunch of them have gone missing over the years (see linked article).
The best option seems to be lunar meteorites.
You can get tiny bits or dust of moon pieces that have naturally fallen to earth at some point. That’s not nearly as cool as some dust or a rock collected by an astronaut.
Might buy a lunar meteorite anyway.