I helped my friend design his house. He bought several design books with basic plans for houses. We combined a couple of the plans to sketch out a basic floor plan and dimensions for what he wanted. He took that basic plan to the lumber yard. They had an architect they worked with who turned it into official blueprints. I don't know how much it cost, but the lumber yard took the cost of the drawings off his materials bill when he bought the materials to build the house.