What is a average price people charge to hang&finish drywall ?

This is a bit vague to give you an accurate answer. How large of an area do you want to average, your state, midwest, entire country. In the midwest it runs around $25 per sheet mud included.

In Texas to hang drywall, if you can get the hangers without using a company, it will cost you $4.00-$6.00 a sheet depending on the difficulty(barrell ceiling, cathedral, etc.). Finishing cost is about three dollars more per sheet for a level 3 finish. Most drywall companies work here for about .35/ft or about $14.00/sheet, and that includes the nails, tape, mud, corners. It excludes the rock.