Smart Phones that can capture GNSS, Wifi, Bluetooth signals etc. have dropped substantially in price. Instead of using some custom hardware solution, it is normally cheapest just to get a "supermarket" phone as a data collection device:
All the phones listed are capable of hosting an Entity Agent of yours.
If you cannot afford new phones or want to reuse an old phone then most phones no more than 10 years old are probably OK.
Pagers may be cheaper providing a very limited Personal Console but NOT they recommended in locations with cell phone coverage.
