Many sellers are reluctant to "give away" their homes at a price so low they feel they'll regret it for a long time. In Harvey Araton's recent NY Times article he revisits the real estate doldrums of 1993.
When he sold his apartment in a problem-plagued Brooklyn Heights co-op for a song, he later came down with a bad case of real estate regret. As a cure, he revisited the place.
I found the similarities of todays market compared to the early 90's to be interesting and wonder if some of us will be doing the same in 20 years or so.