I was in Macau in 1996. Than all the casinos were from STDM, using the same chps, openned 24 hours a day.
There is a chip dealer in Macau- Filatelia Nga San ( contact Mr Ma, and refer my name).See the site , the adress is http://ngasan.safeshopper.com ,or www.macaustamps.com, he has some Macau chips for sale in the site, but you can ask him for others.