Since 2015 visitors from most western coutries don't need a visa with costs for entering Indonesia.

Basically ther'e three types of relevant visa, depending on your intended legnth of stay.

Visa on Arrival

The visa on arrival you get at your entering port at the immigration desk. It's just a stamp in your passport and it is free of charge. Be aware, that it is valid for a stay of 30 days and not extendable.

Visitors Visa 30 Days

The Visitors Visa 30 Days you get at your entering port after having filled the imigration card. It costs 35 USD or 30 €.

A potetential change you will receive in Rupiah at a farely good rate, so it is reccomended having the amount matching.

This visa is valid for 30 days and extendable once for another 30 days, e.g. at the imigration office in the city of Siantar. The extention costs around Rp. 355.000.

Visitors Visa 60 Days

For the Visitors Visa 60 Days you have to apply in advance at an Indonesian emassy or consulate. It costs around 50 USD/€ and is valid for 60 days. It is extenable up to four times by another 30 days as mentioned above, so you can extend your stay up to six months before you have to leave the country.

For furthr information please refer to an appropriate Indonesian embassy using EmbassyFinder.com.