Thanks for the suggestions Kai. Yes, i realize that in most cases these spears would not be thrown. That's why i agree with you and would be more inclined to go with a hardwood. I would image that when fighting with a spear the shaft would need to be tough enough to take some pretty good wacks.
Is there any particular hardwood that you would suggest? Of course hardwoods, especially exotic ones, don't seem to come cheap and i don't know if anyone sells them in 6 foot poles with a half inch diameter.