Rockstar prices GTAIV: Lost and Damned -- £13.60/1600 MS Points!!

[Mirson]

According to IGN, the story will take 12-20 hours. Also there's new content. That seems pretty reasonable. Ratchet & Clank: Q4B was only 4 hours long and costs $15.

http://xboxlive.ign.com/articles/947/947252p1.html