You can get them at the Grady dealer. You need to buy the underlying switch that has a little bulb in it. Rocker tops sold separately if the writing has rubbed off. Make sure you get the foam gasket if you replace the switch.
New wire marine has everything you will need. You can contact them directly if you don't see what you need. Multiple sites describing naming nomenclature for these switches. You can pull them apart and replace the bulb if you are in the mood for some microsurgery.