It is very sensitive to talk about price in business. Because it can influence a deal if price is not reasonable. It is the same thing in jeans manufacturing. Here we gathered 4 points which will mater the cost in jeans production. Hope it helps you to understand why the price is different.
1 Material: Material takes about 1/3 of the total cost of a denim. The higher price of material is, of course the higher price denim wear will be. Compare with none stretch denim, the stretch jeans cost higher. Here is a reference price comparison.
Cotton stretch>TR stretch>Polyester stretch.
2 Designs: How designs influence cost? See the picture below. Of course the cost will be fifferent between complicated jeans and simple jeans densigns.
3 Washing: Washing is very important in denim wear. In this step jeans can be washed in the expected color. Also price is different for proper color and craft works.
4 Quantity: The number of quantity also cause different price. Smaller quantity increase the production cost.