online retailers

Your website offers the unique ability to sell directly to consumers. However, not everyone is comfortable providing their credit card information on an unfamiliar website. People may also wish to use a rewards membership with their favorite bookseller to buy your book. Therefore, it is wise to supply multiple purchasing options in addition to your own personal online store.

Bookstores may also check your website to see if you are supporting them by including them as a purchase option, so if you want to give your distributor its best shot at getting a corporate buy for your book, be sure to include purchase links to the corporate bookstore chains. If you want to get support from the independent bookstore community, then you'd better also link to IndieBound. Of course, there is the bookselling beast that is Amazon.com, but be careful not to irritate bookstores by linking only to Amazon. Sign up for the affiliate programs of the aforementioned retailers for easy linking options and to get yourself an extra little piece of the pie.
Here are links to the most common bookseller affiliate programs:

Amazon
IndieBound
Barnes & Noble
Borders

If you want to build strong support in your local market, you might also consider linking to specific bookstore websites in your area. The more purchase options, the more likely your website visitors are to buy!