you could order one online but that would take a while....tractor supply has them though if you have one of those around....or your local dealership, they will be pricier but still less than 5 bucks
i always put a dab of silicone over the clip so it cant really rattle off or anything and its easy to find then. buy freek and batts case saver so when it happends again you dont have a hole in your case.