Makoman82
There are many factors that determine the cost of a house.
The material will remain fairly constant no matter who builds the house.
The difference in cost is infinite:
-how much of the project gets subbed out to subcontractors
-there are different price levels of subcontractors (size of the company, do they have an office, number of workers, speed / skill of workers, amount / quality of equipment, do they offer benefits, ect)
-size of the general contractor (generally speaking bigger outfits have more overhead / nicer offices / more employees / more equipment , ect) smaller generals may not have an office or employees therefore do not have to charge as much per project. Companies that do more work generally have better buying power with their subs and suppliers which keeps cost down but those savings get chewed up in overhead.
-What does the general contractor value their work / time at. Some builders price their work at 20%+ over the cost of the build where as others may price their work at 7%.
-How busy is the contractor. If they are already busy they may charge more because they do not need the work. On the other hand if someone needs the work they may charge less.
-plus a ton of other factors
At the end of the day the customer needs to educate themselves on who they want to use. After 20+ years of being a contractor (2nd generation) it amazes me when owners do not do their homework on realtors , architects, and builders. Go with someone you like and get along with because it is an important decision. Get to know each of them and see how they work. Lastly do not make the choice based solely on cost (if you intend to live in the house).
Sorry for the long post

Lou