When Sylvester Stallone wrote Rocky, he was really broke, had to sleep on bus stops and sell his dog, Butkus, for $40 to get money for food. Well after he had sold the screenplay to Rocky, he tracked down Butkus and bought him back for $15,000 because the owner knew who he was and knew he was desperate to get him back. Stallone has said that Butkus was worth every penny.
EDIT: He wasn't homeless during that time, remembered that wrong. He was homeless during "Italian Stallion"