I also needed a new Dewalt battery, tho mine was a 14.4V. 89 bucks was
the best i could find, or 50 for a used one on Ebay. Then I found a
rebuilded. I got a new 2100Mh 14.4v battery core shipped to me for 39
bucks. I just have to put it in the old case and make 2 solder
connections. If you can afford the time to ship him your old battery,
he will do it for the same cost.

http://www.wcbatteryrebuilders.com/

they are is California.