I suggest you check up on the shipping laws for primers. I have forgotten all the details, but it is NOT just like shipping ammo. There are Hazardous Material connotations with them, at least for shipping in the USA. Whether or not those connotations and resulting restrictions are really necessary is a moot point, as the law is the law, unfortunately.
There may even be restrictions on how many packets of primers can be shipped in one box. I simply have forgotten. I think this is governed by the Department of Transportation, but perhaps a licensed dealer who handles primers can respond here with the current regulations. I know there is a HAZMAT fee for shipping that is generally more than the shipping costs themselves.
DK - are you up on this?