Landscape Friendly Website Header Illustration

I am looking for an Illustrator who must have a proven portfolio of a high standard. The illustration is for a web hosting company who are having a new website re designed. I am actually the web designer and developer of the website but require an illustrator to create me a great looking header.

I have the idea's of a friendly landscape with a illustration of the data center building in it. The data center building should have a wonky looking sign at the top of it with the companies name on it.

The client has given me these links as examples of illustrations that they like.

http://www.pixelthread.co.uk/
http://www.fatorcriativo.com.br/#home
http://www.iwit.nl/
http://www.1024media.com/
http://www.arbel-designs.com/

The budget for the Illustration is around £15-£20 per hour £140