Putting a tag inside a pack of cards would be relatively simple. There are many businesses that sell RFID inlays or labels that could be placed on the inside of the box before the box was folded and glued. Avery Dennison and Smartrac are two of the largest providers of inlays, and there are many smaller companies that could handle small orders. I recommend searching RFID Connect to find them.
—Mark Roberti, Founder and Editor, RFID Journal