When my son Sean was a boy, he had a zine, The High Flying News, which went out to all of his friends. It ran for over a hundred issues and went to probably twenty-five copies at the peak of its circulation. Now and then one of his buddies would send him an article or story or artwork for the zine, and when they did, I always sent them extra contributor's copies, along with five dollars in payment. Marianne and I were very careful to inculcate Sean with what I consider to be a core moral value: The artist always gets paid. I put special emphasis on visual artists, since they're so often ripped off, cheated, and badly treated. But it applies equally to writers. We're artists too.
Above is a promotional snippet for the Harlan Ellison documentary Dreams With Sharp Teeth. His opinion on this matter is intemperate, angry, obscene -- and absolutely correct.
This cannot be said too often. What separates the professional writer from the amateur is money. If you're a professional, money flows to you. If you're an amateur, money flows from you. It's as simple as that.