There are a fair number around. Expensive to buy new, but you never get your money back on them unless you're not only an active stone fossiker *and* prepared to spend a lot of time turning them into something that will sell.
Ours was bought for the interest of seeing what was inside the geodes we found when out walking
I know someone who took it up, and gave up tumbling or cutting and polishing his own stones, but instead scoured the shingle beaches after rain looking for small pretty stones. He mounted them in pendant mounts and gave them a coat of varnish
It works incredibly well to make shiny looking pebble jewellery, and it sells too.
cheers,
M