Sorry to bring up an old thread. But hit man x and hatty was saying that the resale value of the W140's arent great?
Well from everyone ive talked to $8K for my S420 was a steal. I had looked up the blue book value of my S420 (which i near mint condition with the exception of a few door dings) here was the value with 144K miles (thats how much it had when i bought it, it now has 148K and its only been a month!

)
Retail: $14,300
private: $11,535
trade in: $8,925
So i got it below the trade in price, that sounds like a steal and i could turn around and sell it for $10K if i wanted too....of course i wont because i love the car
EDIT: by the way ive seen more S600's and 600SEL's then i have a 300SDL's. Actually i know of 2 guys around my house that have S600's. But i always see them parked in the same spot when i drive by their houses....cant be cheap to drive them everyday i suppose.