The best place to look for hard to find items is to try the online auction sites.  Ebay or one of the other sites often has unique and rare items, available for reasonable prices.  Also, you could advertise on Craigslist.com to see if any one has these old miniature outboard motors.  Surfing the net by using your browser search box, is another way to find the items you want to acquire.   Posting on messages boards and blogs, like you did here, is another great way to make contact with people who share your interest.  You could search for other web sites that deal with hobbies that collect miniature motors, too.  There must be some online because just about every hobby you can think of, is written about, or has a page or question, on the internet.