Kiwijim - the crossbow on "projects" page has nothing to do with medieval crossbows. Nothing at all. The shape, the stock, the prod, nothing matches. The technology is lightyears from what would have been used on 15. century crossbow. If you think it its correct, then you know nothing about them.
They are tricky to build, if you cut the corners with modern technology and I dont know anybody who would build comercial replica of medieval crossbow, which would at least LOOKED like one, the correctness of construction aside. I know of hobbysts who build very good replicas, altough most uses fiberglass prods dressed and masqueraded as composite prods - which is what I do, hovewer the stock, the bone parts, the friction bedded roller nut, the rope fastening of the prod etc. can be made correctly. But nobody sells it since it is bloody work, which does not pays off.
Yeomanbowman - Gerald of Wales is amusing medieval liar, though most of the chroniclers seem to have their weak moments. I recall Geralds description of crowning of Wales king, which involves intercourse with white as, then killing the animal with swords and eating soup cooked from the meat. But he sure knew how to amuse readers.