Where can I find a back up battery for my iPod, that I can use during air travel?

My family is planning on going on a trip to Hawaii, I heard the flight will be around 6 hours long. I have a video iPod, which I plan to load up with plenty of videos to keep me busy. But I know the battery won't last the length of the trip. Is there a back up battery or charger I can use while on the plane to keep my iPod charged the whole time?

I dont know if there is any battery for iPod.

It is nearly impossible to open an ipod and changing a battery because it is VERY complicated and real easy to mess up your iPod.

An average ipod lasts 6 hours 30 mins though.

http://www.ipodjuice.com/

Check the batteryguys.com ~

iPod PowerStick
http://www.audio-outfitters.com/page40.html

Use rechargeable batteries, e.g 2500mAh, and don't forget to bring extra ones for your flight.

Bon voyage!