The added disc tabs didn't help, but also the reproduction decals. They weren't that nice either. Original non-disc tab add-ons and original in-tact decals, or at least replacements from Kona, will always fetch a little more. I just bought a 90 Cinder Cone to make a ss city bike. Only £45 plus shipping, but it had a dent on the chainstay and the paint, though original, had been touched up. A minter would have fetched much more.
Also small and large sizes can be harder to sell. Size does matter, eh? !8" versions seem to sell the best. And some people prefer Hei Hei's because they're lighter, though more common.