Maybe you dont need to buy one, perhaps you can hunt down one in your home, maybe you have one laying around, look for a ledkeychain or plastic toy or small portable light, old electronics, happymeal toys or even Christmas decoration :p


If you don't connect a led  and run the script manually it should output to the terminal  when change is detected. (so you could already play with it without the LED connected as well)

Thanks for your comment and letting us know you have installed it !