Betterlight sells a Lithium battery for their scanback, the NBMate-118. It was originally made for laptops and portable DVD players, but Betterlight changed the connectors. It lasts for at least a full day's worth of shooting, keeping the back powered on continuously. And it's made in China, so you could probably get it locally. Also, try alibaba.com. It's a great source for almost anything made in China.