The point is not what they cost, unless you just want the money, but how widespread they are. After all, the basic point of a mobile telephone is to ring someone or be rung by someone. So a large number of people have now got some sort of telephone, often living in circumstances under which they had no telephone or paid a lot to share one in some form before.
What is the use of the smartest telephone, at the highest price (or lowest), if there is hardly anyone else with whom to communicate using video calling or some special messaging system or even your latest, very high quality and fast, comms. infrastructure/protocol?
Anyway, I find the sheer numbers quite astounding, just thinking about the ability to manufacture and distribute those numbers of complex, electrical devices, nearly all of which are extraordinarily robust and fault-free under the most extraordinary range of conditions. This and the communications infrastructure supporting them must be one of the great technical achievements affecting and available to the whole world.