Are replacement batteries available for the I Touch

Not from Apple. If you replace the battery with a non-Apple part and/or open the device without Apple approval and/or are not a certified Apple technician, then it will void the warranty if you have one. If not it will void any future Apple support. Proceed at your own risk.

You can get your battery replaced by Apple. Go to Apple - Support - Service Answer Center and choose your country at the top. Select Repair pricing on the left and you will see the price for battery service. Good luck!