If you picked up the limited edition you'll get it free, others will need to shell out $15.
If you're a 'Battlefield 3' player and a PlayStation 3 owner then you'll be happy to know that 'Back to Karkand' is available for purchase now. Unless you bought the limited edition version of course, in which case you'll get it absolutely free.
'Karkand' includes a nice list of new weapons, maps and vehicles as well as a new game mode called Conquest Assualt, which is similar to the existing Conquest mode but with the twist of specifying attackers and defenders.
Xbox 360 owners will be able to get their hands on the 'Karkand' DLC on December 13th.
Source: PlayStation Blog