You won't want chips from Atlantic City. Chips in Atlantic City, with few exceptions, remain redeemable even after casinos close. Therefore, they never lose their face value. So, if you want $500 Atlantic City chips, expect to pay at least $500 apiece. I believe there are some California and Washington card clubs where their whole rack of chips were sold into the collecting and playable set groups, and should be available at a reasonable level. I don't know if many of these clubs had $500 chips, but I'm sure you can get $100 chips pretty reasonably. I don't have any of those chips, personally, but you can see them on ebay, and then try to find a small number for your magic effect.

Best of luck.

Michael Siskin