bfranton - The best listing of these was by Terry Hines and published by the American Revenue Association in 1976, entitled "Special Tax Stamps of the United States." While it is unpriced, it is indicated whether there are examples in collector's hands. The special tax stamps were printed by the Bureau of Engraving and Printing from 1872 until 1953. The small size Retail Dealer in Uncolored Oleomargarine range from 1920 until 1950, when the tax on oleomargarine was eliminated. These are quite common, most can be acquired today for no more than perhaps $15 - 20. If they have coupons at the top (for a portion of a year) they are worth a little more. There is one with coupons for the 1935-6 year (they end June 30) on
ebay currently priced at $60, which seems a bit high to me.