I am leary of these "kit" homes. They probably use the cheapest materials that they can. The route I took was to go to a local architect and pick out a plan. Many localities have different standards for engineering. Shear walls and hurricane straps come to mind. I saw the disclaimer on the Menards plans. It did not inspire confidence. Anyway, after you pick out a stock plan you like you can have changes made and the engineering that goes along with it. This is the time to make any changes. You do NOT want to make changes during construction. After you have the plans you want you can pay for a materials takeoff (list of materials). The people that do this know what they are doing and can steer you in the right direction. We were told to go with a specific type of sub-floor because around here they are guaranteed to get wet during construction. It saved us a lot of grief. I built my house myself. Framing was the most fun of the whole thing. If you get a contractor use his contacts for materials. He can usually get them cheaper than an individual. In my case the lumber yard that supplied my framing package also makes trusses. Once I had the walls framed they came out and measured the house and then made the trusses. I had light storage and attic trusses made. The engineering must be done ahead of time becasue these trusses require stronger headers (beams over the doors and windows) than regular trusses. They are worth it though. It took me 7 years to build my house. We lived in a double wide in the front yard during the ordeal. The double wide is gone. We do not have a mortgage. Life is good.

Also you would probably get a better responce if you posted this question in the Building a Home forum