Live in Flip - Dormer addition

[Peter Pierzchala]

There are older(1940's) ranches in my area that have steeper pitch roofs than typical and even some have existing stairs to a walk up attic. They are small 800sqft 2bd/1ba and I would think the potential to add a dormer with 2 new beds and a bath would be a no brainer. I'm having trouble getting a quote or even opinion of the feasibility to do so since I don't actually own one yet. Are there any general rules of thumb in determining if this is possible while you are only "shopping" for them? What is a reasonable budget to plan for if I would just want a contractor to frame out the dormer and make it weathertight while i took on the labor to finish the rest? I'm located in Connecticut. 

Thanks for any insight!