Customs are entirely the recipients issue. Insured shipping is not cheap, nor is shipping with customs handling included - but on the other hand, the buyer may have to spend many hours personally attending to customs processing (the next customs office might be in the remote state capital, or at some hub airport far, far away), so that $60 extra for a customs processing courier service can be much cheaper for the buyer...
That is, you should negotiate the options with the buyer. But regardless of what he wants, don't ship uninsured if it is a item of relevant value...
Sevo