Walgreens has Scotch mailers on sale for $0.39 each this week. Use the $0.50 coupons from (SS 7/26), to get them free!
At Walgreens, manufacturer's coupons will beep if they exceed the value of the item. Some cashiers will push them through. If your cashier doesn't push it through, try buying 2 mailers and using 1 coupon, to get 2 for $0.14 each!