I got one for about $25 shipped. The lens is fogged I think (it just looks fogged... it doesn't look like any other lens I have). I did run a roll of Portra 160VC through it, and it did fine, but most of the photos were low contrast (as would be expected from a fogged lens). A couple though came out quite nice. The guy at the lab may have upped the contrast on those somehow, but they were very serviceable prints.
I haven't done any more with the Isolette since I got my Yashica-Mat.