The Taiwanese company Beluvv has an interesting spin on kid trackers with its Guardian product, due to ship next month for $30.
Guardian is a disk that looks to be a couple of inches in diameter that you can clip or strap onto your kid. You can set a geofence around your location using a smartphone app, and the Guardian uses Bluetooth Low Energy (BLE) to alert you when the device is getting near — or crosses — the fence line.
If the kid goes astray, you can start a search that alerts other trusted Guardian owners. When the disk goes into range of those owners, they’re alerted and you’re alerted. If the kid good and truly wanders off, the system triggers an emergency search which would alert any Guardian user (and you) if the kid comes into range.
BLE is not as precise as GPS, though it’s cheaper and uses much less power. The app is iOS only; BLE is not widely available on Android devices. And the emergency search feature, which alerts anyone who owns a Guardian to your kid’s presence, is a little creepy — although once you’ve gotten to that stage there are lots creepier things that can happen…