From the postal web page...

http://new.usps.com/cgi-bin/uspsbv/scripts/content.jsp?D=8845&X=#insurance

Insurance
Insurance Rates
You can purchase insurance coverage up to $5,000 for Standard Mail as well as Standard Mail matter mailed at the Priority Mail or First-Class Mail rate. For our most secure service, see Registered Mail for coverage up to $25,000. For articles insured for more than $50, a receipt of delivery is signed by the recipient and maintained by the Postal Service.

You may purchase additional special services when you purchase insurance. For items insured for $50 or less, you may purchase special handling service. For items insured for more than $50, you may purchase restricted delivery, return receipt, or special handling services.

Do not insure your packages for more than their value. The amount of insurance coverage for loss will be the actual value, less depreciation. No claim payments are made for sentimental losses or for any expenses incurred as a result of the loss. (For information on Express Mail insurance, see Express Mail)
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If for some reason the token got lost or damaged I think that the post office might take a serious look at postal fraud, if you knowingly took out $320.00 insurance on an item you knowing know is worth MUCH less!