FAA owners list and sent postcards to
the owners.

I did something similar. I downloaded the list, sorted it for the make,
model, model year, and engine, then sorted it by owners location.
Then I sorted it by owners name. I chose owners who's medicals had expired
and owners who had registered the plane more than 5 years ago. My thinking
was to find somebody who could no longer fly but who had owned the plane for
5 years or more.
I started calling owners in Wisconsin and Michigan that owned Aztecs.
My first 3 cold calls yielded 3 Aztecs and 2 Apaches who's owners had not
advertised the planes but were thinking of selling.
One Aztec turned up only 60 miles from home, 80 year old owner, lost his
medical, but the plane hadn't flown in 9 years.

Jim