I just received mine (this:
DealExtreme: $12.99 Bluetooth 2.0 A2DP AVRCP Stereo Music Receiver and Handsfree (Black)) today in the mail. I gotta say, the battery life truly is pretty bad on it. I need to test it a bit longer, but I'm kind of disappointed in the battery performance. I'm not too upset though, as it was only $13.