Uncle Lloyd's Tips and Tricks:
Jamie Mxacia suggests Max-Gain Systems as a supplier. He notes:
They offer a 20% discount if you buy 10 or more of the same type of rod, and shipping is surprisingly cheap and very fast. They only stock 8-foot-long rods, but they'll cut them for a nominal fee if you want to avoid extra shipping charges for them being oversized. Unless you want to make fiberglass-cored polearms longer than 60" or so, I'd recommend having them cut each rod at 58", which, conveniently enough, is both the maximum length the rod can be before the rod plus the packaging is considered "Oversize 1" and the maximum core length for a Quest-legal great sword, with the other piece, 38", being only two inches more than the maximum core length for a plain sword. While you could opt instead for something like a 48"/48" cut, I find that unless you're making a lot of long swords or short swords, this becomes wasteful: cut a plain sword out of 48" and you've got a dirk or scrap left over, but a 58" piece makes a plain sword and a short sword both close to max length.