New or Used?
A secondhand sextant will save you money, but what if its previous owner has dropped it? There’s often a bargain to be had on auction websites and you might do very well, but it’s worth remembering that the sextant you buy might end up in the liferaft with you in the middle of a distant ocean.
Do you want one that a previous owner may have knocked to within a cat’s whisker of dislodging a key component? It’s a serious matter of caveat emptor. If the sextant is visibly almost new – and you believe the vendor hasn’t knocked it about – you’re probably relatively safe buying second-hand.