My cousin's dog ran away a few days after she brought him home last year, and when she got him back, she bought him a GPS collar.
Well, he was left at a friend's house while she and friend went out. Friend's kids let him into their supposedly secure yard (the pictures make it look quite secure - 6' concrete wall perimeter) to pee, and he found a way out. My cousin got an alert on her phone that he had breached the perimeter, and they were able to head home as soon as it happened. The collar alerts showed that he was basically running in circles around the neighborhood, so she sat down on a corner with treats and waited for him to pass her.
He saw her before he went past her and went to hide under a truck. She kept tossing treats at him under the truck and after about five minutes he let himself be caught.
The collar definitely just paid for itself!