I use a small portable ampified speaker system made by Creative Model CSW5300 Travel Sound used with a lot with notebook computers. It runs on 4 AAA batteries or power adaptor and foldes up small and even has a case. Excellent sound with music and works great with my BCD396T. Check out on the internet searching for CSW5300. The draw back is that it is on the expensive side but very portable and good quality.
Motorola amplified moble speaker (12 volts, which I have LOTS of). $15 at a ham radio swap meet. Works so good, I just bought an other on ebay of under $20 shipped. Will probably mout it in the car- or use it in the garage.