Amazon has coin envelopes at a really good price but act quickly-it changes a lot!
https://www.amazon.com/dp/B000Y50ZD8?th=1&psc=1
$9.10 free shipping
#1 Coin and Small Parts Envelope with Gummed Flap for Home or Office Use, 28 lb. Brown Kraft, 2-1/4 x 3-1/2, 500 per Box (50162)