tertiaryjim - I had not been ignoring craigslist. I am on it every day, and either missed a few opportunities, or never heard back from the few I saw. But last night, a light shined down, and a listing popped up. So, I am the proud new owner of a 36"x 24"x5" granite surface plate and associated stand! WhooWhoo!
Now, to procure some sort of straight edge blank/camelback casting, or whatever I can come up with.