I use these: Sony DRBT50 Bluetooth Headset [1].

I bought them for $115, however some dramatic dynamic re-pricing seems to have occurred recently [2]. Also, I'm a longtime fan of these Sony MDRV600 [3] which sadly appear to have been discontinued.

Also, this Electronic Archicture album [4] is one my regular ambient listens when trying to focus.

1: http://www.amazon.com/Sony-DRBT50-Stereo-Bluetooth-Headset/d...

2: http://camelcamelcamel.com/Sony-DRBT50-Stereo-Bluetooth-Head...

3: http://www.amazon.com/Sony-Studio-Monitor-MDR-V600-Headphone...

4: http://www.amazon.com/Electronic-Architecture-2-Ambient-Edit...