Does batman arkham city for xbox 360 come with the challenge map pack or is it sold seperately?

Hello about a month ago i bought Batman Arkham City for my xbox 360. I bought it brand knew. I was wondering does it come with the challenge map pack for free. Because i saw it on Gamestop.com for $3.00. I'm perfectly willing to pay the $3.00 if it doesn't come with the game, But i don't want it downloaded twice onto my xbox. If i do need to pay for it is it any fun %26amp; worth the $3.00?Does batman arkham city for xbox 360 come with the challenge map pack or is it sold seperately?
Challenge map pack is sold seperately