The factory batteries are all gone. I checked with the manufacturer in China and the outer mold that was used to build batteries for Thales and Magellan Professional is unusable, thus original equipment batteries are far too expensive to build.
However, there are a number of replacement batteries available on eBay. Search for “ProMark 3 Battery” or “111141 battery” and you should get a fairly large list of them. This [ item ] is available for $18.45 including shipping. They are shipped from a location in the United States.
Batteries are also available with free shipping from Hong Kong [ here ] for a slightly higher price.
I suspect that the cell life is not as good as the original batteries, however what choice do you have?