I've been buying and selling on eBay since 1998 and I think shipping insurance is a waste of money,unless the item is worth $100 or more.
I've shipped a couple thousand items and have only had a problem with 2 not getting there.In both cases,they were to the same buyer and I'm pretty sure he lied.He lived in Bozeman,Montana and I called the Bozeman Postmaster after the second incident,and the Postmaster told me that the guy had reputation for making questionable postal claims.
I did learn to ship nothing without delivery confirmation.
If you insure something and it doesn't arrive,USPS rules are that you have to give it 30 days.Then you get a form that you and the shipper both have complete and submit.Then you wait until USPS makes a decision and they have another 30 days to do it.Adding the time for you and the shipper to send the claim form back and forth,you end up with close to 75-80 days involved.Life is too short to go thru that for 30-40 bucks.
Remember,the maximum that you will get is what you can prove that you paid for it.
Also,unless the insurance is for at least $100,the recipient doesn't have to sign for it.
What amazes me are the ebay sellers who insist on shipping a folder like an 108ot or even an 8ot,by Priority Mail when the same knife could be shipped 1st Class for half the cost and just as fast.
The USPS isn't cheap,but it's pretty reliable.Sometimes their shipments get caught in a truck wreck or something like that,and some mail is lost forever.
my 2 cents!
Ron