Doug,
"The Gaming Table" lists over 1,100 casino's in Las Vegas alone. It also lists over 13,000 worldwide. Bear in mind that these are open and closed casinos and just a "ballpark figure" . This would leave one to estimate that the total worldwide chip variety must be somewhere in area of 135,000 assuming an average of ten chips per casino. I am sure others have actually researched this and have accurate data. Mine is just an uneducated guess.