Marcio Rodrigues and his Brazilian colleagues, in a recent commentary, noting that funded researchers in Brazil have roughly $2,000 a year to conduct their studies:

A median cost of APCs equal to USD 2,600 was recently estimated. However, APCs can cost more than USD 10,000. It is noteworthy mentioning that the funding models discussed herein for the Brazilian system and others are not supposed to cover only APCs, but everything else. In summary, it is virtually impossible to cover APCs under these conditions, although it means exclusion from publishing open access papers.

From the paper:

To be inclusive, the APC system must change, and this is urgent. If not, scientists from low-to-medium income regions will not have their science known by the scientific community and the people in general. This situation strikingly contrasts with the widely accepted concept that science is universal by nature, and enhances the already existence of inequalities in science, negatively impacting the scientific-derived benefits for the people(s).