One aspect of the wood question that all of us need to consider is the source of these woods. A number of the woods that we find both strong enough for real training and aesthetically pleasing are fairly rare tropical hardwoods.
I think that we need to excercise some level of consciousness that these woods are from the tropical rainforests which are essentially endangered. It is harder and harder to find these woods precisely because there is less and less of it. That's why a bokken can cost over $100. The problem is that we are affluent enough to cough up that kind of money so the trees are continually being cut down. As much as we like many of these woods we have to ask if it's really ok to keep the market afloat for these increasingly rare tree products.