Indonesia is one of the most affordable countries so it is really possible to travel to Indonesia with a budget of 50k -70k.
Indonesia is quite cheap no matter where you go. I have been to the islands of Java, Bali and Flores as well as sailed through Komodo National Park. Both Java and Flores (you likely won't go here unless you want to see Komodo National Park) are cheaper than Bali. $10 per night or less for a private room is quite common. Local food for about $1. Tourist restaurants $3-5. Beer is roughly $2 per bottle. Rent a scooter for $5-10. Good Luck!!