Hello,
I work with Wacom graphic tablet, Inkling and adobe Illustratoror or photoshop, also many classic techniques (charcoal, watercolor, ink, pen,.. ). You can check some of My work in my freelancer.com portfolio. (if you dont find there anything is style you like, please message me. I'm sure I can find something on my PC, if not I can make you a free sample)
Price (20-100+$/ illustration) depends on style, quantity, technique, size and complexity,
100%custom designs (i don't use free elements, mockups, google or stock images),
I belive book from your link was made with watercolor and crayons
If You have any questions or want to hire me, msg me with details,
Regards,
malajka