Here's an interesting insight that I came across in Faith Popcorns 'Eve-olution: the 8 truths of marketing to women' book. Well actually the quote is from Germaine Greers book 'The whole woman':

"The sharpness of contrast between the genders when it comes to shopping can be seen in the marketing of clothing. By and large, men's clothing is constructed to last; women's clothing, though not at all inexpensive, is instantly obsolete. Menswear represents very much better value for the money than womenswear. What is more, the clothes are expected or altered to fit the man; women have somehow to try to fit the clothes. There are few make fashion victims; all women are victims of fashion."