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Abstract
As of May 2014, the Directory of Open Access Journals (DOAJ) listed close to ten thousand fully open access peer reviewed scholarly journals. Most of these journals do not charge article processing charges (APCs). This article reports the results of a survey of the 2,567 journals or 26% of journals listed in DOAJ that do have APCs. Results indicate a volatile sector that would make future APCs difficult to predict for budgeting purposes. DOAJ and publisher title lists often did not closely match. A number of journals were found on examination not to have APCs. A wide range of publication costs was found for every publisher type. The average (mean) APC of $964 (similar to Solomon & Björk, 2010) contrasts with a mode of $0. At least 61% of publishers using APCs are commercial in nature, while many publishers are of unknown types. The vast majority of journals charging APCs (80%) were found to offer one or more variations on pricing, such as discounts for authors from mid to low income countries, differential pricing based on article type, institutional or society membership, and/or optional charges for extras such as English language editing services or fast track of articles.
Sustaining the Knowledge Commons / Soutenir les savoirs communs 
In response to an offline question, please note that the number of publishers represented in the graph on page 4, DOAJ Journals by APC Publisher Size, is 788. This number is an estimate as the DOAJ metadata for publisher name was not completely consistent so there was a need for some deduplication to calculate publisher size.
Where I can see full Directory of Open Access Journals ?
The Directory of Open Access Journals can be found here: http://www.doaj.org
Thanks for your question!