Dear Six;
There are as many different fastners as fish in the sea.
The place to start is an automotive paint store that supplies the local Body Shops. Take the one(s)needed with you & try to match them.
Next would be a big Body Shop. They will have a thousand or so(new/used).
Private vendors sell these to a number of shops "all over" & have a route they travel. You'll need to meet with one if the above measures fail.
Good luck, John M...
