Article processing charges (APCs) are the fees levied by open access publishers to cover their costs (and make a profit). Open access journals cannot make money by being bundled so easily into traditional publisher subscription packages. Did you know that many open access journals (including some leading ones like PLoS and Frontiers) offer APC waivers for Ph.D. students? It is always well worth asking as two key issues authors tend to have with open access publishing (even though it is overwhelmingly supported by academics) are cost and Impact Factor. It is hard to find an open-access journal that is both inexpensive and that has a high Impact Factor so authors, especially early career researchers, are often forced back towards traditional journal publishing. You would not turn down the chance to publish in Nature after all.
Post by Gareth Dyke, Editor-in-Chief of Biosis: Biological Systems (Published by EAPG), and Historical Biology (Published by Taylor and Francis).