Uhm... you probably missed the part I'm going to color red. Express mail starts at $13.25. You can certainly do whatever you think is correct, but you misunderstand USPS at your own cost.
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Insurance*
Insure your item for up to $5,000 against loss or damage. The price is based on the declared value.
Learn how to file an insurance claim ›
Notes
Available online, at your Post Office™, and at an Automated Postal Center®.
$100 of insurance is included in Express Mail service.