I agree that notability does not apply here, but WP:NFCI does. For non-free images, #4 says the following can be appropriate: "Posters, programs, billboards, ads. For critical commentary." I've usually worked with screenshots (#5), which also necessitates critical commentary. I find critical commentary to mean content from secondary sources about either the image or what is in it. In this particular case, we're talking about costume design, so if there is critical commentary about the costume, it would warrant showing the image of the costume so readers can comprehend that commentary. I can't think of costume images offhand, but American Beauty (1999 film) and Changeling (film) are Featured Articles with screenshots that go with critical commentary. So the question is if there is sufficient commentary in this particular case.  (talk | contrib) (ping me)