Space Rocks and not so rare and all around the world there are events where you can collect them - if you have the drive to collect them.
For science they become less and less interesting as there should be programs that use these rocks for further investigation. A lot of moon rock has been collected in the Apollo project and I understood there is still some left - just in case someone wants to do a research.
So now paying for space rock - i don't think i would do so - i find these stones interesting but only when i personally find one I will feel attached. So I am waiting till we get the opportunity in the Netherlands 