also, I would recommend http://www.nosyuiaido.com (I think that's the spelling)... they can make a bokken according to your size and choice of wood for relatively cheap (I believe a standard shiro-kashi bokken goes for under $100). Give them a look.
You call "under $100" cheap for a white oak bokken? I don't think I've ever spent more than $40 on one. Try contacting Kiyota Company in Baltimore, MD at (800) 783-2232.