I am based in South Africa and there were no official agents here when the Paso was sold. When they officially came in to the country sometime around the middle of the nineties, it appears that they forced all the unofficial dealers to close.
I have been lucky that I haven't needed too much for my bike. I got a brake part from the official agent. Other than that I have used two places.
Gowanloch Motorcycles in Sydney, Australia (
http://www.ducati-gowanloch.com/index.html). I found them helpful and recieved the goods within a week (it is a long way away, and our postal service is not good).
Eurocarb in Reading, England (
http://www.dellorto.co.uk) but this was for spares for my carburretor. I e-mailed over the problem that I experienced and received a comprehensive set of questions to help narrow it down. Once that was done the parts were shipped.
Two good experiences, although you were probably looking for something nearer to home.
Paul