Incidentally, the cards fit very well into our MIM sling plastic bags. Quite useful for holding only what I need for the timebeing - only need like 20 cards at a time.
I bought these Math Dot Cards from a local website:
www.kidsbook.sg
This website seems quite useful:
http://www.childandme.com/how-teach-your-child-math-glenn-domans-dot-method/