I did not see this anywhere, but the game comes with some AR cards and then you can buy additional, but if you are a club nintendo member you can get 3 limited edition cards for free:
http://kidicarus.nintendo.com/uprising/explore-the-game/arcards.html#giveaway
Moving to free.
http://kidicarus.nintendo.com/uprising/explore-the-game/arcards.html#giveaway
Moving to free.