Since before I went to library school, librarians have been talking about a ‘serials crisis‘ — the cost of scholarly journals and periodicals have been increasing far out of step with inflation, publishing costs, etc. for a good 20 years. This is a crisis because library bugets tend to be relatively stable, possibly increasing a bit annually but never at the 10, 20, even 30%+ that the cost of journals increase annually. This has forced some university libraries to make the hard choice between canceling journals, buying fewer books, or letting go of staff; none of these are all that viable because users expect good service (which requires staff) and access to books and journals — especially the ones university staff are published in!
Now if you are a publisher of scholarly journals, you have freaking sweet deal. Your content is basically free — the research itself was paid for by taxpayers, foundations, and grants; the authors are paid by universities; the reviewers and editors are working on a volunteer basis; both the authors and reviewers are just happy to be able to list the publications on their C.V.s; and your customers (libraries) have no other source for the specific content you offer at monopoly prices. I have read that publishers like Wiley and Elsevier have profit margins of at least 35%; that may be including their other, slightly less lucrative enterprises though. A scholarly journal may cost hundreds of dollars for a year’s subscription (and most are quarterly); depending on the discipline it can be much more. <As a commenter says below, some are in the thousands annually.> Keep in mind that these journals don’t exactly have huge circulations — in the hundreds, perhaps; more for some big ones.
Now academics and librarians are not exactly pleased about this state of affairs and beginning in the 1990s, the idea of ‘open access‘ publishing began to be bandied about. All through the 2000s, open access journals began to appear and they grew at a fairly amazing pace. The traditional journals still have a better reputation for quality in terms of peer review, but this is changing as open access, under a variety of models, has grown in popularity. When you consider that big traditional publishers are charging $20-40 for access to a single article, the appeal of open access is more obvious. <A footnote to this: Since this was posted I got published in a scholarly journal in my field, and was offered, by the publisher, a free copy of the pdf article, and a “discount” price of $20 a copy for offprints of the article. I was even allowed to give a limited number of colleagues, friends, or relatives access to the pdf. How very generous. >
I was much less aware of the existence of open access books, but some scholars have turned to this model to get books published (and most importantly, available). I just found out about a directory of hundreds of open access books. You can access it here.
The subject access is mediocre; perhaps in the future they will import subject headings from library records, such as the much more specific Library of Congress Subject Headings. Still, while the collection is still small, it is worth browsing by topics. When it reaches thousands of titles, more specificity will be helpful.