Have you ever wondered exactly why Apple's tiny USB Power Adapter for the iPhone has such a large price tag? The diminutive cube costs US$29.00, while similar USB wall chargers are available from retailers like Monoprice for as little as $6. Ken Shirriff wondered the same thing, so he went all iFixit on one of the Apple chargers and tore it to pieces to see what's inside.
Shirriff found that there's a reason for at least part of the premium price tag, and that's the use of quality components. To quote Shirriff's conclusions,
Apple's power adapter is clearly a high-quality power supply designed to produce carefully filtered power. Apple has obviously gone to extra effort to reduce EMI interference, probably to keep the charger from interfering with the touchscreen. When I opened the charger up, I expected to find a standard design, but I've compared the charger to the Samsung charger and several other high-quality industry designs, and Apple goes beyond these designs in several ways...
Apple's design provides extra safety in a few ways... the super-strong AC prongs, and the complex over-temperature / over-voltage shutdown circuit. Apple's isolation distance between primary and secondary appears to go beyond the regulations...
Apple's iPhone charger crams a lot of technology into a small space. Apple went to extra effort to provide higher quality and safety than other name-brand chargers, but this quality comes at a high cost.
So that's it, then. The next time you walk into an Apple Store to replace the USB Power Adapter that the child flushed down the toilet, you can walk out with adaptor in hand and hold your head up high, for you've bought quality merchandise.