I would insure it to CYA. If the buyer declined to buy insurance because he felt the additional cost was a financial burden, that would send a red flag up to me. Surely he would want it to arrive in good shape and avoid dealing with the shipper if damaged. The only other step you could take is to add yet another outer box to insure "shock" resistance. But again, why could a buyer afford an expensive item and not want to insure it?
Good luck
Good luck