The local hardwood supplier here has it for $2 a foot, for a 3/4" x 3.75" board. Its exactly the thickness I want, and its already planed on two sides. So for $550 I can have a ridiculously heavy workbench that will last a lifetime. There is some wood that is cheaper, but its not already milled to the thickness I need, so I will have to feed the board through the table saw, which is a pain and wastes a lot.
I know its pretty hard to work with, and will need to be cleaned with acetone to remove the oil on it before gluing. I assume its very stable? A big concern of mine is the bench staying flat over time.