Good judges are not impressed by expensive displays. They look to see if you've followed good scientific methods, properly labelled data, etc. Parents and others should not be involved in a project. Scientists very seldom work by thmeselves. It is routine for them to consult others for help and advice.
Parents can help round up materials, give advice, and help with display construction.
See also Frequently Asked Questions . Parents must have a science background in order to help their children with a science fair project. Students should choose projects that they can handle primarily on their own. However, if parents do need help in assisting children there are many people willing to help, including teachers and people in the community. Frequently Asked Questions on how much parents should help.