RiechmannsRelics, you have a B-5 type 2, made about 1928 or so. Yours appears in need of restoration, but they're an easy machine to work on. Very early Porter-Cable sanders, like the B-5, B-4, and B-10 sometimes go for hundreds of dollars in good shape, but can be found for far less if the buyer is patient and willing to do some repair work. Price is effected mainly by the condition of the worm gear, the presence ort absence of the rear roller, the amount of wear from poorly tracking belts cutting the frame, and so on.
Your sander uses a 3"x24" belt, not usually seen in big box stores but easy to come by. I favor Norton belts from McMaster-Carr.
Whatever you do, any worm drive sander or saw should have the oil checked before running. Properly lubricated, a worm drive sander will last for generations; run it out of oil and the gear will rapidly become metal dust.
-James Huston