Earlier quoted context omitted.
It's like the $80 magsafe charger. Thing probably costs $3 to manufacture and distribute, but good luck using your macbook without one. Simple price gouging, but most customers are happy to pay.
Someone did a detailed comparison between the $19 Apple 500mW cube charger vs a no-name $4 lookalike. Short version: the former is an engineering marvel of efficiency, compactness, and safety ... while the latter is likely to kill someone. You may not appreciate the "diminishing returns" of increased quality for increased price, but Apple's bottom line shows a great many do.
There are thousands of examples of iPhone chargers & cables melting down.