Most first quotes are wrong because the enquiry was thin, not because the supplier guessed badly. Five pieces of information move a costing from a range to a number.
1. Category and capacity
“A backpack” can cost three times “a 22 L panel-loading commuter backpack with a padded 15-inch laptop bay”. Capacity in litres and one sentence of construction is enough.
2. Quantity per colourway
Not total quantity — quantity per colourway. Fabric and hardware minimums are per colour, so 5,000 units in one colour and 5,000 units across five colours are different orders at different prices.
3. Destination market
This decides which trim and material tests apply, and testing is a real line in the cost. It also affects labelling requirements. A kids bag for one market and the same bag for another are not the same job.
4. A reference
A photo, a link, a sketch or a physical sample. Any of them beats a paragraph of description. A physical sample beats all of them, because it settles the construction questions nobody thought to ask.
5. Target landed cost, if you have one
Buyers often hold this back, expecting a better first number. In practice it wastes a round trip: with a target we specify to the target, and tell you plainly which part of the brief has to move to reach it.
What you get back
A costing, a materials list, a sampling time and a production lead time. If something in the brief cannot be built at the target, that is in the first reply rather than discovered at pre-production sample stage.