Profit sharing is available for all kinds of merchants, from sports cards to books.
Most affiliates get started by creating a web site about something they are passionate about, like a hobby they already have. They provide useful content, newsletters, and other services to their site visitors. Once they realize they can make money by referring their visitors to trusted merchants, they research the different profit sharing plans and select a merchant with a good profit sharing agreement. Then, they add links to products or services. Once they are making some income in one niche area, they often decide to branch out and repeat their success in a new market by creating a different web site.