There is no need to buy any more gimmicks for this trick...anywhere...anytime. Why not, you ask?
Simply, on the instructional DVD, Erik shows you exactly how to make your own gimmicked cards for this trick or any other trick of this type that you may think of on your own. He even tells you the best "spray" to purchase. I assure you...making a new set of gimmicked is very easy.
Plus, it's not really a secret...a lot of cards/card decks use this product e.g. the Invisible deck, for one.
However, as "girs..." suggests, you can always get 'em here.