The hardware you can pick up at the dealership for a buck or two, and it's always readily on hand in the colors that you need.
Or, alternatively, some car parts stores have those aisles with those "HELP!" product bins, of manufacturer-proprietary parts? You might find them in there as well.
But I wouldn't bother trying to find a car parts store that has one - you could probably travel to your dealer in the same time - certainly less than it would take you to try to drive to three or four car parts stores until you found one with a "HELP!" section that stocked your part.