In astrophysics we now have Open Journal of Astrophysics that is basically an overlay on top of arxiv. https://astro.theoj.org/ It is now catching on with ~ 200 papers published last year, after some of the astro journals started to charge the Golden Open Access publishing fees. I think now people realize how crazy it is to pay for hosting a PDF and for sending your draft to a few referees without paying anything for their work.