I couldn't find "padded envelopes" at the PO (the free ones), so I bought a padded one (1.89) and put Priority Mail sticker on it. I was surprised that the cost was over $14. to mail (bc it wasn't too heavy). I learned that you can order padded Priority Mail envelopes for free online (usps.com). Mailing in the PO Priority Mail padded envelopes would have cost $7.25 to mail.
Sooooo, I ordered 15 padded envelopes and some labels this morning. Free. My F8s are on the way.