Photos to the left are ibeacon wrist bands that you can buy for the purpose of IOT. The price is as low as about $7 each, but buying in bulk is the cheapest way to go. 

The concept on this project is fairly early , but non the less a cool one. I plan to use Raspberry PI to monitor proximity of the BLE wrist bands. The  Wrist bands have a permissions list, you go somewhere your not supposed to then it will alert staff and the user with a vibration or beep depending on the ibeacon band model you get.