> wheat is wheat, but an iPhone and an Android phone aren't totally fungible.
You can also use branding-slash-marketing to make your fungible product seem less fungible. Witness, for instance, how cattle ranchers used marketing campaigns to turn "Angus beef" into a premium, name-brand product (http://bbq.about.com/od/beef/a/Angus-Beef.htm) that customers don't believe is directly substitutable with unbranded beef.
You can also use branding-slash-marketing to make your fungible product seem less fungible. Witness, for instance, how cattle ranchers used marketing campaigns to turn "Angus beef" into a premium, name-brand product (http://bbq.about.com/od/beef/a/Angus-Beef.htm) that customers don't believe is directly substitutable with unbranded beef.