1. Don't insure your item. Insurance is way overpriced because of fraud and those who package poorly. Instead, package it so they can't break it. Also, if you ever do try to make an insurance claim after hundreds of calls, months of waiting, and man-weeks of your time, you'll realized you earned less than minimum wage collecting.
2. It will cost you at least twice as much to take it to a shipping store and have them double box it. Maybe triple. If you're ok with this they will packiage it securely.
3. If you package it yoruself in a bombproof package and print your label online, it will be quite affordable. a 30 lb package generally in the $40 to $60 range, dependding on where you ship it.
4. The shipper is responsible for delivery to the buyer. Your contract ends when the buyer recieves it in good condition.
Jerry