I'm absolutely pro-FOSS but also want to point out that just the licence cost comparison here isn't too meaningful. Licence + maintenance cost fould be a much more sensible figure (and much less likely to be zero).
That is true. But paying for commercial software doesn't free you from having to maintain said software. So while some software might be easier to maintain than other, I think it is fair to just compare the license prices if you have no additional insight into the organization and how their IT operates.