Don't know if you are a BMWMOA member but they have a members only
"Flea Market" with 37 K bikes (of various vintages) for sale as of this minute. Don't know if it's still posted there but there was a guy who had a late "classic" (mid 90s?) K1100 Special Edition bike for sale there- and it was listed for a long while- dude wanted 7000k PLUS $$
YES it was beautiful. Did it seem "worth" his asking price? No way in H - E - double hockey sticks (but I drooled all over that ad for months just the same).
Seems to me that the original STYLE K bikes aren't worth nearly what they SHOULD be. Considering all you get in terms of reliability, rideability, etc. they really aren't selling for shit.