I didn't get mine by going to target, I have a Action Replay DS.Which allows you to basically create your own codes by changing the Hex Values through the games coding and saved games.
I don't normally use my Action Replay, only to put on Unlimited Star Power and bullet for Mario Kart DS lol.
Action replay goes into the Gameboy Advance game slot, and the hex's are transfered from your computer through USB.
Its basically letting you to play the way programers never wanted you to. Not something Transformers DS woudl like to find out but I figured I'd share...