The realist answer:
Buy The Legend of Zelda Tears of the Kingdom. It's Nintendo, they're never going to price drop so you might as well buy it new. Nintendo's motto after all is "If you missed our launch experience of buying our new games or system? No sweat because we always keep our launch prices!"
Final Fantasy XVI can definitely see a sale by the end of this year. And maybe by the time you finish Zelda there'll be a sale for FFXVI.