Kingfisher Woodworks is capable of making very fine wooden weapons for training and use.
http://www.kingfisherwoodworks.com
I personally [highly] recommend Kim Taylor's work as well.
http://sdksupplies.netfirms.com/
The thing about these folks is that they CAN make you just about anything you would want! I would suggest that you first pick a type of sword style you want to study. They can make you a relatively "generic" bokuto that will work well for just about any style of swordsmanship you would do, but if you know what you're going to practice, they can make something designed with that style in mind. That's where the real quality in custom bokuto shines through.
Also, a good practice one will be solid and shaped well enough to really be a potent weapon. Even though it doesn't have a sharp edge and it's made of wood, you should show respect and take it seriously.
Another option is Purpleheart Armoury who offers a somewhat generic model, but I'm sure if you talk with them, you can get it more suited to you. Their products are very popular with European sword folks, so they are probably doing something right (or wrong, depending on how much you like Euro swords

).
http://www.woodenswords.com
SwordForum International seems to support Simbatta's bokuto, though I have no experience with their stuff and quickly browsing over the page makes me wonder about the "custom" value you're getting. I could be wrong though!
http://www.simbatta.net
Best of luck in your hunt, maybe someone else has an even better source than these
