I have just tried mine out. The exact model you list, the BK 08.
It sounds good. I have only tested for a few minutes, but it paired up instantly and just worked. I have tried incoming calls, and it switches over to the call correctly and back to the music. The buttons work as expected, controlling calling and music playback.
I walked away from the phone to check the range, and I experienced a skip or two beyond 5m distance, but when in normal range of the phone, it's flawless.
More about the quality. I have reasonably good ears, having owned etymotic ER4s before now and consider myself a minor audiophile. From a limited listen, I have no complaints about the quality of the stream.
I was expecting to hear encoding artifacts as the material listened to was MP3, and afaik, the a2dp device will encode for transmission using the SBC codec. No obvious negative effects were detected with my admittedly average Technics headphones. If anything, the audio loses a little definition and punch. Not the same as a wired connection, but easily good enough for me.
I have enabled the a2dp registry tweak in the Kaiser tweak tool.
I bought from an ebay user called phone_base, paid £18 including postage, and received the item after about 18 days.
Very happy, and pleasantly suprised.