Many of us have horrible delays going to our local post office. I would estimate the last 3 times I had to go, the lines were at least 45 mins long. As a result, I only use the Priority Mail Flat Rate Envelope which went up to about $11.50 this week. It is the one Priority Mail item that does not have tracking, however, and would not use it for more expensive items. You can typically stick a "small video 1096-S" box inside of the envelope that gives extra protection. I got this idea from cheapbatterypacks.com which is used almost every time I order.
The Priority Mail feature is required to use the "auto" PayPal address system to print labels on my computer, and have it picked up by my daily postman. It prints out a little customs information included in the label, so I don't ever have to go to the post office.
The buyer MUST check the PayPal option of it being "goods" for this auto-address option to show up. If seller categorizes payment as "service" or "other" it won't give the PayPal printing option. You cannot use the cheaper First Class Airmail with this easy PayPal system.