Pokemon Go Plus at Amazon for £16.81 (Prime) £21.30 (Non prime)

The Pokémon GO Plus is a small device that lets you enjoy Pokémon GO while you’re on the move and not looking at your smartphone.
Compatible with iOS, Pokémon GO Plus connects to smartphones via Bluetooth low energy and notifies players about nearby Pokémon and PokéStops.
This accessory cannot be used without the Pokémon GO app and requires a compatible smartphone.