There are many ways to buy content on the Play Store: debit/credit cards, carrier billing, Paypal, and gift cards. The latter is one of the least complicated options since all you have to do is buy a card from the store, enter it into your account, and you're good to go. There's no need to worry about bank cards, carrier fees, or a Paypal connection. You can even gift these cards to friends and family members to encourage them to buy content.
Now gift cards are coming to Indonesia — one of the most populated countries in the world. They'll be available in 150000, 300000, and 500000 Indonesian Rupiah values (approx $11.37, $22.76, and $37.93, respectively) and will be sold at Indomaret stores. Once the gift card balance is redeemed on their account, Indonesian users can purchase content from the Play Store, Play Books, Movies, and Newsstand.
It's likely that Google Play gift cards have been on sale at Indomaret for a while, but they were just officially added to Google's support pages. In case they're not already sold there, the deal might be fresh and you'd have to wait a little to be able to grab them.