A coworker told me that when she thinks about her clothes, she divides the cost by the number of times she has worn the item to get the "cost per wearing," and then she decides whether it was a good deal. I do not think about clothes this way at all.
For example, I rarely wear ties, so in terms of "cost per wearing" I would be better off buying a really cheap tie since I will not wear it often. But I look at it the other way around: a person who wore ties often would need a lot of them, but I can spend my whole "tie budget" on just a few really nice ties. Therefore, I tend to buy expensive ones.
My coworker's model of things strikes me as funny for another reason, too. The more clothes you have, the less often you will wear any one piece. So in terms of "cost per wearing" reasoning, buying a new piece of clothing decreases the value of all the clothes you already own. So it would be counterproductive to buy new clothes.