I recently picked up 25mm Vittoria Rallys on Amazon for about $24 each.
It appears they are still available.
They definitely have the look of old school gum wall tubulars or clinchers. I've not ridden them yet and I know some tubular fans do not care for their ride quality. Since I'll be running mine on a '64 Schwinn Continental, they should be a huge improvement over the original wheels and tires.