PNAS -- Cozzarelli et al. 101 (5): 1111(Sub only)
PNAS is considering moving to an open access model charging more for the publications. This editorial is about a survey they did to the publishing authors. The result was a 50% in favor of an open access model but the authors would only accept to pay 500 dollars for the paper. This price, according to the editor, is a quarter of the the real price.
I guess the move is not for soon , but they are considering it.