Ellen Wexler: What Open-Access Publishing Actually Costs
http://chronicle.com/article/What-Open-Access-Publishing/234108/

Schaubild von Ubiquity Press
http://www.ubiquitypress.com/site/publish/

"Up to 99% of the cost of publishing is spent on peer review. Let me
illustrate that with a simple calculation. About half a year ago on
the Scholarly Kitchen blog it was reported that the technical
preparation (xml-coding etc) and hosting costs an average of $47 per
article at PubMedCentral
( http://scholarlykitchen.sspnet.org/2015/04/08/revisiting-the-price-of-posting-pubmed-central-spends-most-of-its-budget-handling-author-manuscripts/ ).
Any other publishing costs are essentially those associated with the
organisation of peer review (and profits, of course). That means, the
cost of peer review is an average of $2953 per article published in a
typical hybrid journal with APC of$3000, and an average of $4953 in a
typical subscription journal with revenues of $5000 per article. If
these figures are correct – and I have no reason to believe they are
materially wrong – the cost per article of technical preparation is
less than one percent of the average per-article revenue of a typical
subscription journal.

So, massive savings could clearly be made." (Jan Velterop in Liblicense am 28. September 2015)

Shieber 2012
http://archiv.twoday.net/stories/75229491/

Update:

Klaus Mickus stellt die exorbitanten Gewinne der Verlage den Kosten anhand eines Journals gegenüber:

http://de.slideshare.net/klausmickus/mickus-oa-tage15