Some resources I've recently used are Dave Roosevelt at Seattle Used Bikes. I believe he used to own the Ducati dealership there. He helped me with Keihin carb parts and advice.
Seattle Used Bikes - SeattleUsedBikes - Service for Life
He sent me a couple of links for parts guys, mostly used I'm assuming
www.ducpower.com
https://www.facebook.com/UsedDucatiParts/
I recently connected with the guy at ducpower.com and bought a used airbox from him. Great to deal with.
For electrical issues, these guys have been great to deal with and they made up a regulator/rectifier that is on its way to me now
Michael Heth
motoadmin@motolectric.com
(415) 992-7840