There are no other devices that work exactly the same way as the smartthings arrival sensor.
The least expensive method is to use software that runs based on your phone. You can use the built-in location services or you can use a service like life 360 which has an official integration and also works in the UK.
The other possibility using hardware is an IBeacon. You can find these for as little as £15. The problem is that these have to have a receiving station. There are two ways to do this. You can put the IBeacon at home and put the receiving station software on your phone. This works well with iPhones, not quite so well with android phones, but in both cases it can use up a lot of battery.
The alternative is if you have a tablet that stays home, preferably plugged in. You can put the Receiving station software on that and there won’t be any battery issues. Then each person carries the Ibeacon with them, which is very similar to carrying the arrival sensor. This is what we do at my house. We have a tablet on each side of the house which is used as the home automation center. It also runs the IBeacon receiving software, so we didn’t have an extra cost. If you do have to buy a tablet for this purpose then you have to divide its cost over the total number of beacons you have coming and going in your household. But again the tablet can also be used for other purposes.
The following thread discusses various presence options: