I am from India. I think Google play gift card is not available in India till now. I will tell you a method through which you can purchase android apps from Play Store in India without credit card.
The only legal way to buy paid apps from Play Store other than credit card is by creating Virtual Credit Card. Virtual Credit Card is an artificial credit card which acts similarly like any ordinary credit card and you can use it for on line shopping. But in virtual credit card you have to transfer the amount first just like debit cards.
There are two trusted ways of creating Virtual Credit Card -
Create Virtual Credit Card from bank - Many banks are having a service of creating a virtual credit card for online shopping. STATE BANK OF INDIA and HDFC BANK are two banks which I have used for creating Virtual Credit Card especially HDFC BANK's NetSafe service is awesome and just perfect for any online shopper. Amount charged for creating virtual credit card is very minimum.
Create Virtual Credit Card from Entropay - If your bank doesn't give the service of creating virtual credit cards then you can use ENTROPAY for purchasing apps from the Play Store. Entropay is an online service which I strongly recommend for creating virtual credit cards, as it is completely safe and secure. All your information is protected by encryption. Creating virtual credit card through is very easy you just need to fill up your details and your virtual credit card is ready in minutes, now transfer your fund to virtual credit card and start shopping. EntroPay is used worldwide and processes thousands of transactions daily. For using EntroPay you need to pay certain charges.
Earlier Google only sells android apps through its Play Store in India but now Google has start selling books and movies also, so this Virtual Credit Card method work perfectly with them also means you can buy android apps, eBooks and movies without credit card using Virtual Credit Cards.
I hope this post is helpful for you.