I think this guy is a Benz neophyte that picked this car up for a decent price and thinks he has a windfall on his hands.
It looks to be a pretty nice example assuming the mechanicals are in order. But based on what he had posted on another thread it looks like he's hoping to get something north of $10k for it. That would seem very optimistic to me but it is "museum quality" so you never know.
BTW my 80 300SD did not have a passenger side mirror when I assumed ownership 8 years ago. I pulled one off of a 450 SEL at the the junkyard and slapped it on mine.