You might want to consider the Sony Ericcson HBH-DS220 Stereo BT headset.
Pluses:
Onboard volume control works with A2DP and v.3.0 firmware.
You can plug any stereo earbud / headset into the unit which is the size of a AA battery.
When you yank out a wire on your earbuds, the above replaceable function means your BT adapter isn't instant junk.
Half the price of the 1800's. Street price in the $70-80 range - delivered.
Cons:
Uses a non-USB funky two-pronged Sony Ericsson charger port.
Link here:
http://www.sonyericsson.com/cws/prod...20?cc=CA&lc=en