There are several websites at which you can get replacements for under $30. Here are two of them

http://www.hangtimes.com/nobsbatteries.html

http://www.batteriesamerica.com

You can get connectors for almost any type of TX and solder them yourself. Your wall charger should work with any NiMH or NiCD battery, just check the wall wart and you will see the output voltage and Ma/Hr.

Batteries are getting cheaper all the time.

Good Luck!!