What is the most used piece of consumer electronics today? I am not so sure about official numbers, but I think it is a safe bet to say that cellphones are at the top of the list. It used to be that only a select few got hold of cellphones, or mobile phones, for business purposes. Developments in technology and the lowering cost of production have made sure, however, that the average person can afford cellphones.
There is the question of the cost that network providers charge for their services, though. At Cellphones, you can read about a study done in San Diego focusing on the cellphone bills of people residing in the area. It is a little old, though, and the figures may have changed since then. However, it might still serve as reference material.