Illustration for Children's Book

I am looking for an illustrator to work long term with our company who create children's picture books.

This job is for one 'sample' illustration only, so I can test a few illustrators.

Please respond with the cost for one, full colour illustration based on the text below;

'Say, "Hello!" to your neighbours everyday,
Just a smile and a wave as you go on your way.'

The illustration should be appropriate for young children, ages 3 to 8 years

Please include in your quote the rate for a complete book of 12 or 24 illustrations as well, so I know what price it would be when it comes to doing the full book.

The book size is 9" tall x 6" wide

The file needs to submitted in full size (300dpi minimum) psd file that I can open in photoshop.

I would like to see a sketch first and be able to make revisions

I have provided some samples but I am open to any style

Please ask if you have any questions!