It depends...
There are two ways to sell and I've seen both before
Situation #1 You need a sale very soon! ... for whatever reason (there are many reasons why) you need a sale ASAP. In this case you might actually lower your price just to make sure you get your sale.
Situation #2 You need the sale but can afford to wait out the market. A friend of mine has a fairly nice Triumph TR3A, he restored it himself and now is in the process of selling it (his new "toy" is a gorgeous 1995 Jaguar sedan), he still has garage space and enough current funds to keep the Triumph - within reason - and get the price he wants. He told me this himself, that he started a little higher in price to see if anyone bit, and as time goes on he will lower the price to (hopefully) get the sale eventually.
If you followed all of that, that's why I think there is often a variance in price in the market place. To sell a classic car can sometimes take a little time to find just the right buyer who really wants it, and there are times when the sale has to happen by a certain date and that definitely will affect price, even on E-Bay.