Finally, I bought a Sony B-Trainer at Sony Store yesterday, it seems good for me (can listen to the current running status + mp3 songs and can record the running information for further analysis.
Now they have launched a promotion until end of this month, HKD200 Welcome Supermarket coupon + shoes bag. (I am a Sony member and got their Sony e-coupon code, so more HKD300 less), I paid 1680 and got HKD200 Welcome coupon + Shoes bag.