How much do people care about what they listen to? What kind of pricing power can the best stuff command?

I think it might not be as simple as supply and demand, because a) you can't just trade one piece of content for another and b) the marginal cost is ~$0.

Put another way: there are only so many hours in your life when you can listen to stuff. If Spotify has all the best stuff, it might be worth it to pay quite a lot, even if that stuff was cheap to produce.