Where can I buy 'Crackle' nail polish?

I live in Suwanee, Georgia. The latest thing here is crackle nail polish. I want some real bad. Where can I buy it? (at the average retail store) And exactly how does it work? Do I put one color down and then the crackle polish? Or does the polish have one color and 'crack' in another? Please fill me in! :P