I knew I would get 'in trouble' for using the word 'rare' :)
I really don't know how rare they are. I have never seen them for sale, and I have played in tournaments before and you can never leave the table with the chips. To me, that makes them rare. If anyone else has a set, please post it.
I don't remember when I got them - I found them while looking for something else.
Thanks for looking.