2.3 gingerbread - How to purchase an app on Google Play without a credit card?

I live in India and I don't have a credit card. I have tried using debit cards, internet banking and a virtual credit card from my bank (State Bank of India), but none of them work.

How can I purchase an app (PowerAmp) without a credit card?

Google Wallet is not acceptable because my phone runs Gingerbread and it isn't compatible.