ummmm get the GOTY, it's 38 bucks for ALL of the dlc and that includes getting the bundle instead of the nightwing, robin and skin pack seperately. The catwoman dlc is also part of the $38. I know in the regular version catwoman was a voucher, and if you bought it used you'd have to buy the catwoman pack seperate, but since it's ALL on the disc in the GOTY edition.... i dont' think it matters if you buy GOTY new or used. And NEW... GOTY is $49 at gamestop, same price here and there's only 2 Used copies here atm both for $50 as well. So if you can sell your regular version for at least 12 (lol).... you'd basically just be replacing the game, and getting all the DLC.
This DLC is why i wait so long now to buy any PS3 games, it's friggin annoying. Take Need for Speed Hot Pursuit, the 3 main DLC packs that add more races were already on the disc when the game CAME OUT. They're on the map that shows all the races, yet they're locked out until you buy them..... that's just wrong. An actual expansion fine... but if it's already on the damn disc then I should be able to access everythign on the disc >.< So now I wait, a very long time... to see if something like this version of batman comes out with everything on it like it should be (Mortal Kombat Komplete Edition is another example, didnt' buy mortal Kombat till THAT version came out).