I saw one on E-Bay about a week ago - it had a price of about �300 I think, but it was genuine.
Alternatively you can try net-a-porter or mywardrobe.com as they stock Sass and Bide as a rule. You could always e-mail enquiries at net-a-porter (the link is on their website) as they are so helpful and have always helped me in the past track down items.