There's an exploit for file sharing on the PSnetwork where you can share any DLC for free. Basically, you have the login/ password whom has purchased/ downloaded the content. Use that persons PSN login on your personal ps3 to login to the psnetwork. It'll ask you for CC info, ignore it. Go to the upper right portion where it says "View Downloads" and you'll see a history of what that individual has downloaded in the past. Click on the DLC you want, install, login to your regular account and enjoy.
I did this with all the COD map packs, and most recently the XMEN arcade port. Bear in mind, you can only share 1 account with up to 5 people.