This paper addresses the topic of the article processing charges (APCs) that are paid when publishing articles using the open access (OA) option. Building on the Elsevier OA price list, company balance sheet figures, and ScienceDirect data, tentative answers to three questions are outlined using a Monte Carlo approach to deal with the uncertainty inherent in the inputs. The first question refers to the level of APCs from the market perspective, under the hypothesis that all the articles published in Elsevier journals exploit the OA model so that the subscription to ScienceDirect becomes worthless. The second question is how much Elsevier should charge for publishing all the articles under the OA model, assuming the profit margin reduces and adheres to the market benchmark. The third issue is how many articles would have to be accepted, in an OA-only publishing landscape, so that the publisher benefits from the same revenue and profit margin as in the recent past. The results point to high APCs, nearly twice the current level, being required to preserve the publisher's profit margin. Otherwise, by relaxing that constraint, a downward shift of APCs can be expected so they would tend to get close to current values. Accordingly, the article acceptance rate could be likely to grow from 26-27% to about 35-55%.