The most expensive illustrators are well known and established best sellers. Cost is effected by experience, cost of materials, time it takes to create and how well known an illustrator is.
I have seen illustrations range from $25 per page to $2,500. The average being $240 to $540 per page. As in most cases, you get what you pay for. The cheapest rates are from students or recent college graduates are the least expensive, but their style is most likely still developing and your first page will most likely look a lot different than the last page of your book. Also, the artist may not have the printing experience to create your artwork and you really could have something that is unusable by printers because they were created at the wrong size or resolution.
There are two types of computer illustration, Vector and Bitmap. Most designers create your pictures in a bitmap program like Adobe Photoshop, while others preffer a vector style and use software like Adobe Illustrator.
- bitmap - realistic. can be scaled down in size but not up.
- vector - cartoon style, can be scaled to any size without the loss of resolution.