Per the Ounce
We've been ingrained to think if we buy a bigger product that it's going to cost us more. But like that trip to the grocery store where even though you're spending more on a larger bag of kettle cooked chips, you're paying less per ounce than if you bought the snack size.
The same goes for some designs. When I went to have my contractor price out my adorable and sophisticated clutch design I was a bit shocked to learn the cost of production. But it's small I thought. How could it really cost more than my large tote to produce? I didn't understand. Then I stepped back and realized my tote was a much similar design. With the clutch I was paying for all the folding and twisting of the leather, the detailed pockets, the zippers, the credit card compartments. The works. So even though it was "smaller" it was a more detailed piece and would take them wonder to construct and create.
Keep this in mind when you're shopping, maybe this explains why the "smaller" bag doesn't cost that much more than the larger one. Maybe this is the winning argument for you to get the larger mascara instead of the travel size, or maybe it's just the straw you need to buy that large bag of gourmet candies. Whatever it is, enjoy.