Impossible to give you an answer, too many variables.

um, it is not "impossible" for folks to share their experience.

We're on Long Island and replaced our roof in 2009.
The old roof was cedar shake, so they had to remove the old roof, apply new 3/4" decking and the new roof.
We used Tamko 30 year shingles.
The job cost about $6 Sq.Ft.

http://www.homewyse.com/services/cost_to_install_shingle_roof.html

http://www.gencoroofing.com/Calculator.html

http://roofingcostcalculator.com

http://www.roofcalc.org

Thanks for the responses :)