Hi there!
I'm Nico, an experienced artist in traditional art techniques and any artstyle. I've made cover arts for books and music albums, posters, clothing designs, concept art for videogames, etc. You can find watercolor artworks in my portfolio here, in Freelancer.
About my professional qualities, I'm really perfectionist and like to do my images as perfect and close as possible to the client's demand. I'm constantly asking about the details of the project, showing the work in progress and working hard to finish on time without losing quality.
The price range you are asking for is really low, specially if you intend to sell the book and expect that it will have success. If you don't want to take risks, we could agree on a percentage of your earnings until we reach a fairer price that we also discussed, and from that point you'll have 100% of the earnings, obviously. That way if you don't have luck, you'll only have to pay me 30$. I'm offering this because I'd like that both of us get paid appropriately, it wouldn't be fair to get 25$ if you earn thousands, but also wouldn't be fair to ask you 100-200 if you don't have any earnings!
Thank you for your attention, I'm looking forward to hear from you! Nico.