Depends on the condition. I paid $40 for mine and they are in VG condition with intact headband and clean supple pads. At that price (and the guy delivered them to my work) I was very happy.
I always hate to advise this, but look up past auctions on Ebay and you'll see that they sell readily at pretty high prices these days.
As far as sound quality goes I like them a lot after replacing the internal decaying foam and some basic damping with felt behind the driver. Not the best cans in my collection, but very fun and a distinctive presentation.