Traditional publishers allow booksellers to return unsold books after a given period. Let’s say that the bookstore buys ten copies and 90 days later there are two left. The bookstore has the option to return those two unsold copies and get their money back. If you want to compete with a traditionally published author you need to allow this too.
It is important to remember that the second phase is about providing information. By this point, they are prepared for you to try to sell them something, so give them a break and don’t.