We have one for our attic switch in the hallway. And there's one where the switch use to work some lights on the fireplace mantle from the previous owners.
If Sears or Home Depot or the like don't sell them, look in the YELLOW PAGES under ELECTRICAL SUPPLIES. I'm not partial for a particular brand although when you see one (or a few), ask about its quality and how it compares to 'other brands'.
My best to ya and hope this helps.
PS: Be sure the switch is rated for its intended use ...