I bought a garter belt on the cheap and the little plastic hook that holds the strap that hooks onto the hosiery snapped off. They seem to be interchangeable with other similar parts so is there a website or something where I can find just that part? I'd like to stockpile a few just in case.
I'm not sure what the part is called; I've attached a picture of it for reference.
Try a local sewing store - most of them have the parts in the "notions" section by the elastic, buttons, etc. I usually buy a few at a time to keep for backup too.
I can only imagine any fabric or hobby shop would carry all of what you need. Or even a lingerie shop like Victoria's Secret.
I've made my own garters just by sewing the strap directly to the belt itself. I get too irritated with the plastic hook snapping out of place all the time, so there's always that alternative.
I also can't stand the traditional strap clips. Instead, I use clasps like what is intended for suspenders. It's super simple to just cut off the already existing clip and replace it, if those give you problems as well. =0]