Bob

I've never seen one "fail" since the very early days (early 90's) when some people tried to hand layup their own. With modern baking and prepregs breakages are usually operator error. The most common way is the bearaway after the top mark in big breeze, and not having eased the luff before. When the cartwheel happens and the mast is already under big tension a belt on the water will sometimes give a break a bit below the hounds. Diamond wire/fittings failure will also cause breakage in that mid area. Both of these would not suit the length you want. Also the masts are easily repaired if you know how, so most end up back on the boat. The only breakage that would give you 26 feet is if the hound or stay broke and the pin had been left in the base hinge. They sometimes then break by hitting the gunwhale which is about 4 feet from the base. Usually would happen in big waves if you can't then get the pin out quickly. Pretty rare though as we've worked out to remove the hinge pin and use it in the gooseneck.
The other thing to be carefull about is that the masts are built with a thicker layup around the hound and diamond tang area. You'd have to take that in to account if using bits and pieces.
Another way to approach it is to buy a second hand mast and cut some from top and bottom to get the proportions right. A good second hand Saarberg or Fibrefoam in this country would typically be $3k - $3.5k. Assume similar in US after currency conversion.

Cheers
AUS9