Illustrations for my books

I'm looking to hire a talented artist to create illustrations for my books. The style should depend on the book, and what I'm looking to achieve, so I'm looking for someone who can work with me in this capacity. I need approximately 50 illustrations, so I'm looking for someone with the skill and experience to create that many pieces. Last, and perhaps most importantly, my budget for the illustrations is somewhere between $1000 and $5000. Whoever I select will need to be comfortable working within that budget.