Sam, I have foundthem at antique stores, in the news paper, the want ad digest, the paper shop, and other such classified publications. Look anywhere that seems to have some old tools. Got one at a garage sale. Ask around, get friends to keep their eyes open. Definately check any antique stores in the area and talk to the folks that run them. They may have stuff "out back" or in the cellar, or know of a friend who does. I also look on ebay mainly to see whats out there and what its going for (usually top dollar). Great deals are still out there, but you've got to keep your eyes open....
Happy hunting!
Ed