I've been on both sides of this issue, as a book author and editor, and as a
magazine editor. I've done considerable writing and editing for the Brooklyn
Botanic Garden for almost no money--I considered it a donation for a good
cause--and I've allowed book publishers to use my photos in my books for little
return. (You can see some of my books on amazon.com under Karan Davis
I'm not suggesting that others should do the same, but I would point out that
having photos published can mean a lot to someone trying to break in to the
business. It may be worth "donating" a few images in order to have something
to list on your CV.
Good luck on whatever path you choose.