At $70 (UK£54, AU$99), Sony's SRS-X11 is at the higher end of the micro wireless speaker market, which is rather crowded these days.
While you can get even cheaper Bluetooth models, the SRS-X11 is one of the better-sounding micro wireless speakers and offers 12 hours of battery life.
The Sony SRS-X11 is a very compact, attractively designed Bluetooth speaker that plays pretty loud and sounds pretty decent for its tiny size. It has an integrated speakerphone, can be paired wirelessly with another X11, and offers 12 hours of battery life.
Should cost about one-third less.