When you take into account editorial contributors (£100 per page, or £4,400 per issue), design and art help (£2,900 per issue), hardware, bills, app store charges etc., it all adds up.
So it's not just a "bunch of PDFs" -- it's a complicated collaboration between writers, artists and stores. We want to make it good value, but we're not just reproducing some HOWTOs. We're making new, original, creative content.