I think a related part of Apple's pricing advantage comes from the fact that they are good at taking technologies developed for the iPhone and using it in other places instead of reinventing the wheel for every product.

The iPod touch, Apple TV, and iPad are all variously stripped, screenless, and scaled versions of the iPhone. They share the same processor and underlying OS. This allows Apple to not just sell a lot of stuff, but to sell a lot of the exact same stuff. So not only are their marginal costs lower from buying in bulk, their fixed costs of research and development are lower, too.

Could an iPad's cost $499 or an Apple TV $99 if they didn't sell the iPhone? Probably not, and definitely not if they wanted to keep the kind of margins they command right now.