I haven't bought biking shoes in like 13 years. I'm still wearing the same pair of Shimanos I got for my first mountain bike. They still work.

My guess on the chicks buying overpriced shoes is someone probably told them they would get a better workout with the shoes. I've heard instructors say that in my gym. Then they went to the store and the clerk sold them the most expensive thing (s)he could convince them to buy. And some people just like to buy stuff so they feel like they fit in.

Veronica