Shipping any type of hazardous material by UPS or Fedex will include a HAZMAT fee of about thirty bucks- so keep that in mind if you're selling other than FTF.
It's the same fee whether it's one box of primers, or dozens of pounds of powder...long as it's one box.
This includes primers, and powders.
Loaded ammunition can be shipped by UPS or Fedex ground without the fee, but label as such. You CANNOT ship any ammunition of hazardous components by USPS.