Last year they published a grand total of 8 articles with the editorial staff doing the copy-editing, and web work for free. It is nice they are doing this but it isn't indicative of the cost of hosting/peer review/copy-editing more substantial journals.

As for "peer review", this has no cost: reviewers are not paid.

Facilitating peer review does have a cost. You would be surprised how much it takes to find referees that are both qualified to assess the paper and do not have too close of a relationship with the authors. Then there is the whole thing of getting them to file their reports.

Here's another example, the Journal of Machine Learning Research, where the cost of publishing an article works out to about $10: https://blogs.harvard.edu/pamphlet/2012/03/06/an-efficient-j... (previous discussion: https://news.ycombinator.com/item?id=15280736)

It is literally just hosting in this case.

However, even if you were to pay the people behind the journal for their work it should be fairly inexpensive as long as they did as little as Elsevier does.

I'd be interested to know if there are any additional costs involved to have the journal listed in the major directories, getting/calculating an impact factor, promoting it to institutions and so forth. This example calls itself a journal but looks a lot like a website and not much more.

Yes, JCGT is fairly small but it does have a pedigree. After the fifth and last of the Graphics Gems books series, the Journal of Graphics Tools was founded in 1996 as a venue to continue publishing gem-like articles. It was a print journal owned and published by A K Peters. Back in 2012, most of the editorial board resigned and immediately refounded as the open access, online Journal of Computer Graphics Techniques. No, it's not as prestigious as, say, Proc. SIGGRAPH. But it is reputable and you can still trace its lineage a good ways back.

(Disclaimer -- I'm co-author on a paper published at JCGT and have been a collaborator with a few members of its editorial board. It's still a highlight of my career have published with Tom Duff of "Duff's Device" fame and had the paper get a nice twitter mention from John Carmack: https://twitter.com/ID_AA_Carmack/status/846525438797086720)