Look at the techniques used to make Aluminum frames. The frames are expensive to make, as the hydroforming process t'ain't cheap. Steel frames can be made using straight tubes for the most part, a much cheaper process than having to form.

The funny part is a Ti frame. With about 2 pounds of Ti in a frame, you are only talking $200 at most in raw materials (if the tubing is purchased in quantity). The cost of a frame is not just the metal or carbon in it - it is the forming, assembly, welding, etc., that makes a given material cost what it does.

Carbon should be expensive - the manual layup in a mold is expensive, lots of labor. Plus the material isn't cheap, either.