Asking
Berapa harganya? ‘How much is it?’
Shorter and just as common:
Berapa? ‘How much?’
Ini berapa? ‘How much is this?’
The opening move
Do not counter with a number immediately. Indonesian bargaining starts with a reaction.
Mahal! ‘Expensive!’
Said with a smile, this is expected and slightly theatrical. It invites a lower offer without making one.
The core question
Bisa kurang? ‘Can you go lower?’
Kurang means less. This single question does most of the work. If you want to name a figure:
Lima puluh ribu, boleh? ‘Fifty thousand, ok?’
Boleh on its own, from either side, means agreed.
Where it stops
Bargaining belongs to markets, souvenirs, art, clothing and transport agreed in advance. It does not belong in a warung, a supermarket, a pharmacy or anywhere with a printed price.
Harga pas means fixed price. If you hear it, or see it on a sign, the conversation is over and pushing further is rude rather than clever.
The part foreigners get wrong
The gap you are arguing over is usually small in your currency and meaningful in theirs. Bargaining is a social form, not a contest, and grinding someone down over the equivalent of fifty cents reads exactly as it would at home.
Aim to land somewhere both sides are content with, and stop.
What you’ll actually hear
What the book says: Bisa dikurangi harganya? What you’ll hear: Kurangin dong.
Kurangin is the Jakarta form, with -in replacing the formal -kan. Dong is a softening particle with no translation, somewhere between “go on” and a friendly nudge.