If the bikes were mine, my first priority would be to clean them up and see whether I could get them mobile again. Until you've done that, there isn't much to be said about value. In any case, whatever the value is it is mainly in their historical significance, so it will be maximised by having as much information as possible about them.
They don't show many design features in common with the first range of Konas and the 1988 Kona brochure says that Joe Murray had been designing for TBG 'for many years', so they aren't necessarily the immediate predecessors to the first bikes branded as Konas. The first Konas had geometry 'borrowed' from Brodies, and at first glance these Cascades may pre-date Brodie's involvement. But we could maybe tell how close they are to the geometry of the first Konas if you took some measurements and posted them here - I'd say c-t seat tube, c-c seat tube, c-c top tube and the head tube would do it.
Another way of dating them could be to see whether the frame serial numbers tell us anything (underneath bb shell?)
I take it you're in the US and I think there'll be a lot more memory about Cascade over there than there is here, so the mtbr vcr forum might be one good place to ask for information. Another source could be Joe Murray himself. I believe he is accessible via Voodoo, and if you can't find a way to get through to him, Hilts on this site might be able to help you, as I know he has corresponded with JM about his own early Konas.
They're certainly very interesting bikes, well worth restoring, and it would be nice to find out more about them.
