Let me pose a question.

I am going to write a biography of Diane Easby. I ask Dick Greenhause, Captain Birdsey, M.Ted and a few other Mudcatters to share their thoughts. I explain to each of them that I am writing a book and I would like to use their words as commentary in my book, but I can't pay them. At best, I will buy them lunch. They agree to do so.   The book is a runway best seller and I am now purchasing a summer house in the Hamptons.

Do I owe these people money?