Thanks to Ian Song from Simon Fraser University for providing this information about the OA APC charged by Hans Publishers’ Hans Journal of Neurotechnology (in Chinese). This is published separately as a good illustration of the variety of models within the article processing fee approach.
I looked at the web site about the processing fee at http://www.hanspub.org/journal/Fee.aspx?JournalID=582
The processing fee is 1,900 Chinese Yuan (about 328 Canadian dollars) for 8 pages. If an article is more than 8 pages, 100 Chinese Yuan per page will be added to the extra pages. For good quality articles (reviewed by the committee) from low income authors, the charge can be reduced (does not mention how much). If the first author is a student, the student can get 20% off.
This is the first time I’ve seen discounts specified for quality articles and student discounts, although clearly quality is a factor for other publishers as many offer such options as language (generally English) editing for an additional fee. The per-page charge for long articles is one that is used by other publishers. When you think about it, this makes sense; if we’re paying for the service of publishing, it makes sense that the amount varies depending on how much work is needed.