The yellow Duet is a really good find - one I don't have and not often seen. But prices are so wild at times: the best price ever - a few years ago - was £215 for a 4-in red-dot-on-white (reversed, I call it) Polka Dot vase, followed quite swiftly by £225 for a 5-in version of the same. The Intaglio range normally commands the best prices, but ones from the Carré (Escher) range are, surprisingly, not that expensive and although scarcer than Psychedelic often don't reach a comparable price.