The hardest chips to find in that set of 12 are the dragon and tiger chips.

They were sold in the Paulson store back in the day as souvenirs, but even back then, the Tiger and dragon were never in stock. I think someone must have bought all of them. They are pretty auspicious animals in the Chinese zodiac. The Paulson store did not care to order more of them, and in the end just liquidated the rest of the inventory. You will find racks of the other animals sometimes for sale on ebay, but very rarely will you find a tiger or dragon chip.

I have a complete set of 12. It took me years to find those 2 chips. It is not for sale, but good luck! The thrill is in the hunt...