$ versus $$$

When I think about home security systems, I think, Why do we pay so much for something that can be acquired for for so cheap?

You know those door alarms you can buy from the morning or night market? They work with magnets or something. There are two pieces. You stick one end to the door, the other to the door frame. Once the two pieces are separated, it'll go off.

Obviously this isn't some kind of sophisticated system that will alert the cops should the alarm go off. But good enough to alert people. But then come to think of it ah, the cheap system isn't as good because once the door is closed, the alarm will go silent.

HAHa. But who will continue to stay in the house after the thing goes off anyway.