I have a couple of extra electric motors and decided to build a 12" disk sander. The plans are in the book "Building Workshop Stations". Built out of scrap MDF and plywood so the cost is going to be pretty close to zero and it looks like that it should work well. Now the only problem is finding a good place to buy sanding disc. I see Grizzly and Woodworkers Supply handles them but I do not know about the quality compared to price. Where do you buy yours?