Allison yes, it could be commercial. In addition to what Ed said, products like mugs, calendars, tee shirts, etc. are considered commercial use. But prints, no, they are considered art.
Oddly enough if it's published in an art book, like a coffee table book, it's still considered fine art even though it's mass produced.
However, none of this will prevent someone from suing over the use of their likeness. Doesn't mean they will win, but do you have the time and resources to defend it?