I'm sure that works most of the time, Charles, but I can attest that it doesn't work every time. Last year I received three inexpensive chips in the mail packaged the way you described, and all had a "postage due" note attached to them. My post office considered them packages, not non-machinable letters, and the amount I owed was more than the chips were worth.

There are advantages to shipping only in a bubble mailer with tracking, even though it's more expensive for the buyer and seller.