Went to a trade show up here and one of the suppliers of autobody fasteners has them in their catalog along with plastic bolts, fender washers, etc.
In the auto part stores they have them in big divided drawers with part numbers on the outside.
I agree with you about the high shipping costs on small items, a perfect example is Mar-K when shipping to Canada. In some cases shipping ($18.00) is too expensive for the bedroll reflectors they sell.