I don't know how much of the cost of a given bow goes for marketing, but I know how much marketing costs and it's staggering. The reason it's so expensive is because it works, which is funny if you think about it. Hunters are some of the most opinionated folks you'll ever meet, yet here we are paying big money to marketing firms in order for a bunch of suits to tell us what to think. And when they do, we often hold onto those nuggets of belief with religious conviction.
It really gets interesting when a defect appears in a particular bow. If something goes wrong with a less promoted bow, we condemn the manufacturer without mercy. But if a defect appears with a big name bow, we'll rationalize and even blame ourselves for whatever happened.