If you haven't tried it already, you can call www.asseenontv.com at 866-277-3366 and ask if they can help you out.
I'm guessing that Five Star Power Tool is not a real tool company in that I doubt if they actually make anything themselves. They probably just contract with a mfg. in China to have these made for them. If you happen to have a Harbor Freight retail store nearby, I'd take one of the batteries there and see if their batteries might be compatable with your set.
111,111,111 = 12,345,678,987, 654,321