It's so tough with these cars today. So many people selling them THINK they're 'worth' two or three times what a real buyer will write them a check for.
A local lady asked me to help her sell her 1981 280SL Euro 4 speed last Spring. Second owner, 81k miles, well maintained with lots of records and a $5k+ paint job in its original color by a well respected local Mercedes-Benz dealer body shop (yikes!) just a year earlier, zero rust, etc.
She initially told me she was looking for $25k! That's what her friend told her it was worth, so I asked, why don't you try selling it to your friend? "Well, he doesn't want it" In fact, I'm sure nobody wants it for $25k.
I tried to break the bad (yet realistic) news to her. It's probably a $6000 - $8000 car... and I'm talking real cash money, not 'I see them listed for'... but what a real buyer with money in hand, willing to give it to her, will pay.
I eventually listed the car for her at about $14,000, that's what she'd 'let it go for'. It languished on our local Craigslist and on Hemmings through the prime Summer selling months with NO callers, not one. I listed it here on benzworld.org also.
At the end of the Summer I finally convinced her to put it on eBay (stupid high reserve of like $14k). Auction ended at about $6,800. The car has been in her underground garage since.
When you look at these cars, especially nice ones, that run well, they're fun to drive, heck, it's a classic Mercedes (young classic), how can it NOT be a $15,000 car? They're just not, for better or for worse, but if they sit in the garage of an owner waiting for more money, an owner who doesn't use and drive it on a regular basis, they're going to end up with something worth a lot less in five years of sitting than it's worth now.
These will never be short wheel base Ferraris, or even 300SLs to the collector car world. If you're not using them I think you have to take the now dollar and move on with life.
Of course, that's easier said than done for many folks... especially original owners of these cars who bought them new, the were expensive when new and quite the status symbol... now, most are just used cars that trade in a thin hobbyist market.