Initially Audubon painted pictures without thinking of publication, but was persuaded that his pictures were better than ones which were being sold, and so he saw them as a way of earning a living. However, he found it difficult to enter the market for such pictures in the USA, and so in 1826 he travelled to Britain to start looking for subscribers. We hear of the long years away from his family searching for subscribers and dealing with the problems of publishing large colour pictures. Eventually his efforts paid off, and his pictures brought in sufficent income to support his family and his desire for travel.
It's an interesting story, but I felt that if it's supposed to be a 'Rags to Riches' tale, then it could have been structured better to support this theme. Audubon seemed to be losing money throughout, and at one point landed in debtor's prison, but clearly things came right in the end - I'd have liked to have heard more about when the 'break even' point was actually reached. The book's worth reading if you're interested in the subject matter, or in the impressive pictures, but perhaps less so just for the story.