Usually, JSTOR is available through institutions such as universities and libraries. I imagine you could purchase a individual subscription, but I'm not sure how you would go about doing this. Best bet would be to find a local college or library that subscribes.

As far as your other question, there's plenty of information available online for no charge, and there's other stuff you have to pay for. JSTOR falls into the second category.

FYI JSTOR is a database of academic journal articles.