iPod Bluetooth Keyboard

Bluetooth is bluetooth it spends power on the iPod. About the battery of the keybord look at the Apple keybord it's on rechargable batteries or on ordinary batteris size AAA, so you can easy replace them.

http://store.apple.com/us/product/MC184LL/B/apple-wireless-keyboard?fnode=56

Sorry for may mistake yhe battery size is AA.

You mean the cheapest? There are tons of them around $20-$30. Just an example: http://www.dealextreme.com/p/flexible-silicone-bluetooth-foldable-keyboard-black -white-50701?item=4

However, if you want some quality, go for the original Apple one. It's so much better to type on it.

Note that some dealers sell it for considerably less than Apple; for example, http://www.dealextreme.com/p/genuine-apple-78-key-bluetooth-wireless-keyboard-2- aa-36335 . However, I'm not sure it's the latest-gen (late 2011) model and not the previous edition.

have a look on ebay or amazon