Don't go through Amazon to buy this device.
http://www.gomadic.com/
That is the website for it. It will work on a number of different devices with the correct tip. So you can get it for your Sony Reader, cell phone, DAP, etc.
As you can see they do the charger for a number of devices. So basically, get the charger, the tips you might need, and as long as you have access to AA batteries, you can get a charge. Also have a look at
https://www.mobileread.com/forums/showthread.php?t=24059 for a quick review.