Original Xiaomi Miband 2 OLED Display Heart Rate Monitor Bluetooth Smart Wristband Bracelet - £13.35 @ BangGood
After searching through the previous deals, this appears to be the cheapest it has been.
0.42inch OLED display screen with touchpad
Support Heart rate monitor
Passometer,Fitness Tracker,Sleep Tracker,Message Reminder,Call Reminder
Water resistant (IP67)
20-day standby power
Sleep-cycle smart alarm
With a Dialog II 4.0 bluetooth chip, ADI sensor
Running MIUI Android 4.4 and above versions; For iphone 4s/5/5s/6/plus ios 7.0 and above
Unlock your Mi phone without a password
Stylish band options (incl. wrap-around and leather)
Thanks @Dabstar