battery replacement of 3gs

I have a iphone 3gs. Its battery is dying. Standby time has reduced drastically. I go to sleep with 100% wake up with less than 50%, with wifi,3g,2g,bluetooth off.

I want to replace the battery. Reading all reviews on web, it seems 3rd party solutions are big gamble. So I will fork out few more bucks.

I read it costs $80 + $6.99 + local taxes. I live in India, so where do I end in my phone, how soon can I expect it back.

More importantly does apple still change 3gs battery. Its been a while since the model has been stopped.

Before you guys say shell out some more bucks and get new iphone, I am perfectly satisfied with this phone. I don't particularly like the box cut look of 4/4s, and 5/5s/5c are going to cost a lot more to me.