revision preference src: Bidding anonymously in a 1980 auction, he paid $935,000 for one of the rarest stamps in the world, the British Guiana 1856 1c black on magenta. <SEP> tgt: He bid anonymously in a 1980 auction. He paid $935,000 for one of the rarest stamps in the world, the British Guiana 1856 1c black on magenta.