This is cut and pasted from an email from The Yahoo Rocketbook group.
"I've been trying for some time to get my original Rocket Ebook battery
replaced, and using this forum as a resource for options. None of the
options I looked at were currently available, so I started searching.
I located a company advertising custom battery packs, and emailed them.
They described their services and pricing, and I sent them my
semi-disassembled rocketbook battery pack. Yesterday, I received back
the replacement pack, reassembled the Rocketbook, and wala! it worked
like new. It is holding a charge and the backlight works just like
the old days.
The Vice-President, Michael Wollack, was very prompt emailing answers
to inquiries on their capabilities and status of the order. The
service was prompt, cost effective ($21 plus shipping - $3/volt) and
I assure you this is not a commercial, and I am not affiliated with
the company in any way. I just wanted to relate my good experience,
and update the battery resource info on the site."