Good question...having the shop available for use, machining the parts myself, and Kevin E sending me a free carbon shaft (he shipped it yesterday!) - total cost will be quite low.
I really only have to pay for the titanium itself, about $20 or so per axe - oh, and I'll have to purchase some epoxy to bond the shaft to the parts.
However, I have spent many hours working on it, design/re-design, manufacture, including a small accident Sunday requiring me to remake the head stem and spike (my skills have dwindled over the years). If you have access to the facilities required, then it is definitely a project to take on...if you are going to farm out ALL the work and material, I imagine a "one off" would be quite expensive.