Observers of monograph publishing often complain of a lack of transparency around publishing “costs”. There is the sense that BPCs are arbitrary and do not relate to real costs. In a landscape study covering eight European countries (Austria, Denmark, Finland, France, Germany, Netherlands, Norway and UK) my colleagues and I came across BPCs ranging from €500 to €18,500 ($585 - $21,640). Here I aim to explain why by looking at what services are offered for a BPC and also explain why coming up with precise and comparable costs is problematic. The figures are taken mainly from UK and global English-language publishing, however, the basic considerations do not differ greatly from those found elsewhere. A glossary of accounting terms is provided at the end of this article. One purpose of this article has been to indicate that BPCs and APCs are not the same and to show how greater transparency can lead to getting to reasonable BPCs with less acrimony than has been the case with journal APCs.