batteries
you guys talking about batteries why not use rechargables i got some uniross hybrio they are like rechargables because you can recharge them obviously but they are also like normal batteries cos they hold there charge longer
dont know if it helps but they are on ebay uniross 9v hybrio batteries 5 for £19.99 i know its a lot but at least you can use them over and over and they are 200mah also no memory so you dont have to discharge them before you recharge
let me know if it is of any help