A while ago I got a paper published in a Springer journal. While finishing up the publishing process I got the option of having "Open Access", but at a price:
Authors opting for Open Access in the Springer Open Choice program, agree to pay the article processing fee. The standard fee is US$3000. Customers in the Americas will be charged in US dollars, and customers in Europe, Asia, and Africa will be charged the equivalent fee in Euros. VAT and other applicable taxes are not included in the standard fee of US$3000, and will be added according to the requirements of the country where the order is placed.
$US3000 seems a bit much for open access to a little maths paper. I put a more up to date version on the arXiv anyway. It's no wonder that the general public doesn't quite know what scientists get up to when so much of their output is in non-open journals. Walk-in access is diminishing too since libraries are switching to electronic subscriptions and you sometimes need a student/staff login to use a computer in a library (I think that's the case at UQ these days).