That link does not seem to work correctly or is not a valid page on there site. Is the link below by chance what you were looking at on the GT40 forum.
if I were doing a lot of custom headers, then yeah I could justify the cost, but for a one time, one off deal then to expensive for my liking. Still a great idea though.
I am actaully modeling my headers for my supra swap in Solid Works (3D modeling program incase you are not fimiliar with the name). Should help save some trial and error mishaps, time and material waste.