Approach your local Fine Arts School and ask them if they'd be interested in a co-op excercise for their students as an open competition to submit designs for a commercial project.
Give them all of the necessary parameters and make it a matter of a prize for the winner in the form of a gift certificate for art supplies. This will allow the school to stimulate the students and offer them real-world experience in many ways. If the Art School or Academy is adverse to this idea, approach your local High School Art Departments, they are always open to creative and meaningful interests. I would do this before simply hiring someone who already possesses a professional portfolio. ( I am reminded of a quote from the Joyce Carey novel; "The Horse's Mouth" ; in which the principal character artist Gully Jimson remarked when looking at a painting that; 'Amateur's, do much the more interesting work'.)