The cost of a rod I build for you will usually cost between $350 - $700.
The maker of the blank will have the most impact on the cost of your rod.
The price of a custom built fly-rod will depend on many factors including:
Cost of the blank, reel seat and handle, components, decals, and thread-work.
Blanks I use include: TFO, Winston, North Fork Composites, American Tackle Company, H&H, MHX, Striker and many others.