Phone

 A smart phone today is a small computer. With apps, its functionality is equal to several expensive devices (with some inexpensive devices, too) of, say, 1990:

[Computer]

Calculator

GPS 

Digital camera & video camera 

Tape recorder 

Dictionary 

Metronome & tuner 

Pedometer  

Compass

Flashlight 

Music player 

Phone (and video phone) 

Identifier of bird species by song 

Mirror 

Alarm clock and timer 

Whatever other apps you want for games / entertainment... or for your own hobbies. 

This could easily be in excess of 1000 dollars if purchased separately, and there is a convenience factor of not having to have separate devices. 

Seen this way, I will never buy a metronome or camera unless I get more seriously into certain hobbies. Nobody buys a GPS anymore if they have a phone. 

It is true that my phone is not a hat, a microwave oven, a piano (though it can mimic instruments in garage band). It is not a shovel or hoe or firearm; not a coffee grinder or espresso maker.  

(This is wonderful, except that it often gets replaced in favor of a newer model, so it is not quite as inexpensive as it sounds. Also, you must have computer too. And I also have a smart watch.)