If its a large placard, you can get clear, white, or colored label material from Office Depot or similar and just print your own. If small stuff you can do the same or go to the local engraving shop in the yellow pages.
Using the Windows paint program, (as I often do to edit, organize and submit photos here at VAF) I produced and gave FastSigns full scale computer renderings of what I wanted. The placards and graphics were produced in triplicate and ready for pickup the day. The cost was similar to a large deluxe pizza.