There is a seller on ebay, who also has their own website;
http://www.newpower99.com/
This seller also includes a 'tool kit' with most Kindle batteries, as well as a link to a video on 'how to' which is quite diferent in 1st gen thru 3rd gen
I have not purchased from them yet, but wanted to pass this along.
I have NO affiliation with these sellers, just found them searching.