Angry birds trading cards are found in all places in the world except Africa (outside of Egypt). Each card pack has a code to unlock Lime Bird. The cards are $19.99. Only Orangebird763 can make cards.
Front of Angry Birds Space and Heikki Card
Back of the Angry Birds Space and Heikki Card
Angry Birds Seasons Merchandise Card (The back side is just blank.)
The bonus card for Bad Piggies. (Front)