Online booksellers have captured a very large portion of the retail book market over the past several years. Companies that have a large online presence, such as Amazon (which also owns the popular The Book Depository) and Barnes & Noble, now dominate this market. Over the past 15 years, the number of independent 'bricks and mortar' bookstores has fallen.

Briefly explain what role costs may have played in explaining the large decline in independent booksellers.