I first bought a 2G Coby mp3 player that was powered by a AA battery and had excellent sound despite being a cheapy plastic thing. I think I bought it right before I was given an iPod 2nd generation Nano, also a 2G, as a gift.
I still use a newer Coby mp3 player in the office and as a knock-around player. For the money, Cobys still has good sound - at least to my ears. Their players look like plastic toys but honestly their cases and buttons haven't broken on me yet. During the summer mine stays in the hot car sometimes.
The battery is still going strong, sound is still quite acceptable.