It is really unusual to see the 'rare' badge on an early 1990s Mercedes sedan...a diesel to boot! But this isn't your ordinary Mercedes 240D or 300D - its a 350SD, only sold in 1990 and 1991 with a total of less than 5000 produced in both short and long wheelbase versions of the W126 Sonderklasse. This 1991 Mercedes-Benz 350SD W126 is for sale in Scottsdale, AZ for the premium price of $12,500 buy-it-now via ebay.