If somebody wants a working demo of a Proximity Tag, then just drop an email to harald.naumann (at) gsm-modem.de. The evaluation kit for a Bluetooth Low Energy IC I have in my office. One of my customers is in the key-fob industry and developed a keyfobs with 868 MHz radio inside. Bluetooth Low Energy also called Bluetooth Smart is on 2400 MHz. An 2400 MHz antenna at a key-fob is an easy task.
At Kickstarter they try to collect USD 50.000 to start the project. If you like I can ask what my customer has to charge. With a little luck we can use the enclosure of the key-fob on 868 MHz.
http://www.kickstarter.com/projects/rowdyrobot/tod-connect-real-world-actions-to-mobile-devices-a