This in a nutshell explains why you don't purchase these sorts of games when they're first released. Just wait a few months to buy the version that has all the DLC on the disc, and likely at a lower cost.
That's what I plan to do for ARKHAM ORIGINS. That should be out just about the time the last story DLC is released. Just what happened with ARKHAM CITY.
@shadowx: That's like calling Wednesday. They were obviously going to do a DLC version.