I'm currently trying to figure out if book illustrations would work in this digital age, for example to help promote a book on social media, or to enliven a digital publication, and so I am currently doing custom book illustrations for free.
Because I create custom illustrations, I can create images you will hardly find in stock photo databases.
I remain the owner of the art, but I would give you a non-exclusive, transferable, permanent, irrevokable world-wide, fee-free license to use the illustration(s).
What I kindly ask in return is that you permit me to publish a short (100-200 words) part of the text from your story along with the illustration, crediting you, of course. Ideally, the text should give the reader an idea of the story. The idea would be to see if this could help promote your book.
I can't accept tight deadlines because drawing is labor-intensive for me.
The way I work is I buy and read your book to get a feel for the tone and to understand the story, the context. I'll ask questions: things like what actors you think the characters resemble. I believe it is best if you choose the part of the text you think would be a good candidate to use as inspiration for the illustration.
I then make "mood boards," basically images from the internet collaged into one: photos of people and poses and moods to show to you so I can get a feel for whether I am on the right track.
Then I create design sketches and show them so we can discuss, and then I make the final drawing.
I can't promise a quick turn-around time, but if that is okay with you, I might have time for a collaboration!