Here's why.
You can't go, "Oh, this Macbook from Apple is really expensive. I am going to go buy a cheaper Macbook at Pear."
Basically, no other company makes the same products as Apple. I mean, Asus, HP, Acer, Toshiba, and all those laptops are basically the same thing, while Macbooks are COMPLETELY different.
Same goes with iPads. Other tablets are all same and boring, but iPads have access to the App Store and other cool Apple things.
So you end up buying the expensive stuff from Apple because you can buy it no where else.