I have a Hemi XK and I paid $1000 to have both drivers and passengers side manifolds replaced a few weeks ago. This included new bolt sets, gaskets and manifolds. It could have been cheaper if there weren't so many broken bolts. There were several on each side. I checked around and it was a little high but in the ballpark. This included a 12 month 12k mile warranty on the work... Because of the issues with these things the warranty was important to me.
2008 XK Hemi w/QT2
Superchips Flashpaq 3875 running Mileage Tune (for now)