The motor is in the lid, right? The tub is either porcelain or some metal like aluminum. You can check on eBay where they are offered from time to time to see what the beginning bid is and then track the item and see what its selling price is. They are usually found in the category Small Appliances--Other, but searching under portable washing machines or portable washers might be a good way of finding all of them.
Their biggest market was to young families with a child in diapers immediately before and after WWII because the metal tub could be placed over a stove burner and diapers could be boiled in it or at least washed at very high temperatures. This probably rapidly lost its appeal for many reasons, especially with the invention of modern synthetic detergents which did not have the dissolvability problems sometimes seen with old fashion laundry soap and the gradual reduction in the phobia about germs. especially around babies.