Provided it's just a flat piece of plastic, check with your local plastic supply houses to see what they can do for you. Often they can custom make something for you. After you have the size, you can either cover in wood grain vinyl or paint to your liking. Gauges are available in a variety of colors & finishes - pick what you like and run with it.
Otherwise, look into marine salvage yards to see if they have what you are looking for.
Good luck!