illustration for children book

I need illustrations for an upcoming children book. Specifically, i need 20 sets of images, each set consisting of a vehicle and a place. For example, one possible set is a police car and a police station. As the target audience is children, drawings should be lively, simple and attractive. All images must be original and all rights would belong to me upon completion. Images should be submitted in jpeg format (approx 500 by 500 pixels and 300dpi)