Pricing enchanted items
Why each enchant combo has its own page, and how to use them.
Why one price isn't enough
An Elytra with Mending and Unbreaking III and one with a curse on it are worth different amounts and can't fill each other's orders. So every combo has its own page, with its own chart, listings and orders.
The main item page
The main page shows the cheapest copy of any version, because that's the cheapest way to own one. Its buy orders are for a plain one. Other versions lists every combo that's listed or wanted, with its cheapest price and best order.
Curses change the price
The cheapest copy is often the cheapest for a reason. Check for Curse of Vanishing or Curse of Binding before you buy, particularly when a price looks too good.