Blood Dragon Armor DLC for Dragon Age Origins Xbox 360/Xbox One

I recently bought the digital copy of Dragon Age Origins from Microsoft Store for Xbox 360 and I have a question about the Blood Dragon Armor DLC.

From what I understand, the only valiable way to get the aforementioned DLC for Xbox 360/Xbox One version of the game is to get a code for the DLC from retail copy of the game, which is, I belive, near impossible to do today.

Is there any other way to get this DLC legally? Or is the possibility to get it long gone by now?