@deqing tells us that he is working on a version for CC2541 and founded a interesting device to hack: HAVIR HV-101 & HV-102. It may be the only low cost BLE product with a reprogrammable controller.
It has a button, 2 LEDs, a buzzer and debug pads. That basically everything we need. I've put it's photo on https://github.com/DeqingSun/CC2541WristBandHack