Illustrator required for iPad application.26 animal characters required for a book

Hi we have come up with a concept for an interactive iPad book app but we require 26 Animals as Transparent PNG files (Vectors)-We will invite you to our dropbox for the images.We are open to suggestions on how the animals look but this is aimed at young children so maybe a cartoon style approach would be good.
We will supply the list of Animals from A-Z 1 animals for each letter. I will supply the list to the winning bidder. A sample of your work would be good, estimated time frame etc. This could lead to a long relationship with an established app development company in the UK. Payment will be made on completion of the job and we are happy to provide a contract.
We need these asap and are happy to negotiate on cost