Two bags of the same model in different condition are not one item at two prices. They sell to different people.
What moves the number
Corner and edge wear, which is where a bag shows its life.
Hardware — plating loss, tarnish, a zip that catches.
Interior condition, and whether there is a smell.
What comes with it — dust bag, cards, strap, charm.
Whether the shape has held.
How much you can say about where it came from.
Why two of the same differ
One listing shows all four corners, the zip worked, and the lining turned out. The other shows the bag propped into a shape it does not hold. Describing bag condition.
How to find out rather than guess
Compare completed sales in the same condition with the same extras, and discount for anything missing. Do not compare against retail: the room is pricing a used bag.
Certainty belongs in the number too. If you cannot say where a bag came from, that is a real discount and an honest one.
On authentication
Nobody settles it over a video call. Show what the bag carries and say where you bought it. A careful "I cannot confirm more than this" prices lower and sells cleanly; a confident claim you cannot support does neither.
Questions people ask
Does a missing dust bag matter?
A little, and more on collected pieces. Say it.
Is corner wear repairable?
Sometimes, by a specialist, at a cost. Assume not when you set your number.
Does a smell really lower the price?
It is the most common reason a bag comes back. Say it and price for it.
More: pricing bags, selling bags.