It's traditional that Thai people haggle over the price of things in the market. However, the way Thai people shop has changed over time. There are more supermarkets, department stores and other shops with fixed prices. Small shops and street shops are the places where people tend to haggle most as prices are often advertised at a higher level and the shop expects customers to ask for lower price. It varies how much they ºÍ¡¼èÒ¹ bog pan, possibly starting from 20 Baht but often not more than 300 Baht for things worth not more than 1,000 Baht.
Normally, goods that are haggled over are clothing or handcrafted products. Luxury or everyday goods have fixed prices. Food is not considered expensive, even for Thai. Definitely no haggling at the supermarket, but you might ask for a few Baht off at the market, e.g. bananas at 23 ß - ask for 20 ß.
Surprisingly some people ask for a discount at restaurants and the
discount is often 10% of the food price (excluding drinks).
They ask when they get the bill:
|ºÍ¡¼èÒ¹||to say a higher price when expecting a customer to haggle|