There are a few nice looking K1's on Ebay right now, and not much action on them. Given how cheap decent K100's are, I think even a very good K1 is hard-pressed to push much over $4k. It's seems like the rare black ones command a noticeable premium over the red or blue.
'11 Ducati Multistrada 1200S Sport "Stormtrooper II"
'09 BMW HP2 Sport
'98 Ducati 900SS Final Edition "The old whore"
'93 Ducati 900SS "Slightly older whore"
"Gentlemen. You can't fight in here. This is the War Room!"