These might work:
http://www.allelectronics.com/...MINI-SPEAKERS/1.html
From the All Electronics site:
"Crisp, clear amplified sound for your iPod or other portable music player. Requires a bit of minor surgery. Cut off the proprietary Sony-Ericsson plug, and attach a 3.5mm stereo phone plug and a power source (batteries or power supply). Color-coded wires in control cable are easy to identify; red and black for 5 Vdc power, blue, green and copper for left and right audio signal. 35" cable between speakers. 15" cable between speaker and connector. Operates on 5 Vdc (power source not included). Speaker dimensions: 2.1" high x 1.8" wide x 1.2" deep. Of course, if you have the Sony-Ericsson phone/music player that these were designed for, just plug and play."
Take care, Joe.