2 tips are covered in this article:
1) Print shipping label online to save time and get free delivery confirmation
2) Print shipping lable via PayPal without getting payment.
If you go to the post office, delivery confirmation is $x--they raised the rate again so I don't know what's the current rate, I'd say about $0.7.
Here is how to get free delivery confirmation (priority mail) or for $0.18.
1. Use PayPal, if you receive the PayPal payment--everybody know it.
2. What if you don't receive the payment by PayPal? For example, your customer paid by money order, or you want to send a gift to your friend. Use the link below, no PayPal payment needed.
3. Dont have a PayPal account? Use www.usps.com -- priority mail only--Create an account or login, use print a shipping label. It allows you to print the shipping label with or without postage (free delivery confirmation included). If you print the label without postage, you can just attach your own stamps (buy stamps on eBay below face value to save several cents).