Coins generally aren’t tax-free just because they’re silver. There’s often a purity factor involved.
My understanding is that the one of the few circumstances where a silver purchase is tax-free is if the item is listed in the “bullion” category. Commemorative coins aren’t necessarily tax-free in most jurisdictions, as far as I know.
You might want to do some Google searching for your buyer’s state or province’s sales tax regulations and exemptions. Many buyers don’t know them as well as one would think.
