Sometimes I want to read a paper, but only subscribing members can have access. They want me to pay a fee in the range of about $30 for one-time access to the PDF file. But I can always go down to the library and read it for free. $30 seems like it would exceed by $20 the cost of simply purchasing that issue of the journal, and all I want is 1 article.

Then I find that many other papers are free to read over the internet. Why are some free, and some not?

At $30, do they make ANY sales? If it were $5, I'd be tempted to save myself a walk to the library. Any professional is likely to have a subscription through his or her institution. Any non-professional with a passive interest isn't going going to pay $30. (at least I haven't). At $30, whose their target market?

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