Do you think maybe part of it is that casual browsers don't know what a nice bike that is? They see 'Schwinn' and don't know the rest of the story (though you've given them the story, that doesn't mean they can/will read the full description)?

I lucked out last week - sold my 2001 Trek 1000 for $336 plus shipping, which I thought was great. But it's a Trek, and everyone knows Trek. I ended up selling it to someone who bought it as a Christmas gift for his brother.