also remember that if it's lost, you actually need to prove the value of the item, and a sales receipt from the buyer isn't good enough, it needs to be the original receipt from the store where you purchased the item, or they won't pay a penny..trust me, been there, done it.
if there's no original proof of purchase, no point in insuring or tracking the scope, then just use standard post and keep fingers crossed.
tracking itself is a joke, even if it's tracked, if it's 'lost' then the couriers usually say they can't help you and email you a claim form..you pay tracking to feel good you know where the package is in most cases.