http://www.produxcompany.com/display_stands.php
We use these for our cars, several people at the local cruise-ins & shows use these (the base can be weighted with pea gravel so it doesn't blow around). You can have custom graphics made by them, use a local shop, or do it yourself. We just print out two 8.5x11 pages ourselves on heavy paper stock - one is a brief listing of the car specs and the other is a vintage ad. This way we can change it up or update as needed with very little cost.
Whatever you do keep it short and simple.