For 80 bucks you can get this speaker dock for your Sandisk Sansa e100 MP3 player. It runs off of four AA batteries or can be plugged into the wall. There are also audio inputs for other portable devices you may want to hook up to it. As for the Sansa e100, it comes in 512MB or 1GB versions and has an expandable SD memory slot.
Sandisk has also release a FM transmitter dock for the car, retailing for 60 dollars made especially for the e100.(via MobileWack) It’s nice to see these types of aftermarket accessories for MP3 players other than the iPod even though it is for a not so popular player. We can only hope that other manufacturers follow suite.