There is a whole group of Klipsche junkies that loves those things...
They have a older intimate sound - and a lot of history and 'soul'. They had some problems with time alignment of the drivers, that caused a lot of midrange suckout that I believe was fixed in III to some degree.
I'm not sure what they are worth, I know they keep a higher resale value than most speakers, but 550 seems high to me. I'm not an expert on the going rate though. You'll pay extra for the 'history'