Yep, I've been using that kind of hardware for decades, and haven't seen a nice small clip like Berkeley Point sells very often, and never any less expensive when you add it all up.
Least expensive shipping for little tiny things is First Class with Delivery Confirmation using the print-your-own-label-and-postage service at usps.com -- an 8-ounce package goes cross country for under $2 -- so you might try to convince any supplier to check into that.
I've actually succeeded in the past with people sending little LED lights -- they use their PC to print the label, drop the package in the mail, and can check to see delivery was confirmed online, once they have signed up with the USPS to do that, and it's much cheaper than parcel services.