No. If an item has a price tag then you're not expected to bargain. You are not expected to bargain in a restaurant either.
While bargaining is a central part of the Thai shopping experience, you should approach it with a healthy attitude. The point of bargaining isn't to see the vendor lose money, but rather to get a price that you are both happy with. There can be a lot of tooing and froing on price, but it's best done with a smile and a laugh rather than a scoul and finger pointing.
Remember once you start bargaining, if the vendor accepts a price you offer, then you should buy the good. It is considered very bad form to decline a purchase after having a price accepted.
There is no hard and fast rule on how much you should try to get knocked off the price. Obviously in tourist areas, for example Bangkok's Sukhumvit Road, the markup can be extraordinary and you could work towards a discount of perhaps 60-70% off the opening price. In other places though a 10% discount may be more reasonable.
A good way to get some benchmarks is to peruse similar goods in the big shopping centres (where the prices are marked) this should give you an idea of a base price to work around.
Lastly, many stallholders believe that selling to the first customer of the day brings them good fortune for the day. This gives you a bit of an advantage to wear the price down a little more. You'll know you were the first if, after the sale, the vendor gets your money and touches all their products with it.
Please find below some of the more frequently asked questions (FAQ) people have about travelling to Thailand. We've tried to answer all the most frequently asked questions, but if you have another query about Thailand, please try our Travelfish messageboard.
Is it possible to rent rooms or dormitories for long periods of time?
Rooms: is a fan room ok, or should I budget for air-con?
Should I take my own padlock for the door of my room while travelling in Thailand?
What should I do if a bag is stolen from my room or dormitory while travelling in Thailand?
What standard of acommodation can I expect for US$5?
Why are there so few dormitories in Thailand?
Can I drink the tap water in Thailand?
How can I avoid MSG in Thailand?
How do I avoid peanuts in Thailand?
I have a food allergy - will I cope?
Is there good vegetarian food in Thailand?
Is western food available in Thailand?
Are the ferries in Thailand safe?
Are the trains in Thailand safe?
Do they trains run on time?
Is it easy to hitch-hike in Thailand?
Is it easy to rent a car or motorcycle in Thailand?
Should I get a tourist minibus in Thailand?
What is Bangkok's bus system like?
Which is the better way to travel around Thailand - train or bus?
Are credit cards accepted in Thailand?
Are there ATMs in Thailand?
How can I have money sent to me in Thailand?
How can I send money out of Thailand?
Should I bring travellers cheques, credit/debit cards or cash to Thailand?
Should I tip in Thailand?
Are leeches a problem in Thailand?
Are legal drugs cheap in Thailand?
Do I need a prescription in Thailand?
Do I need malarial medication in Thailand?
General food and water precautions in Thailand
General health advice for Thailand
HIV/AIDS in Thailand
Is cholera a problem?
Is heatstroke a problem in Thailand?
Is medical care cheap in Thailand?
Is medical care in Thailand good?
Is rabies a problem in Thailand?
Schistosomiasis in Thailand?
Traveller's medical kit for travel in Thailand
What about dengue fever in Thailand?
Will I get diarrhoea in Thailand?
Are there many internet cafes in Thailand?
Can I travel with a laptop in Thailand?
Is there ADSL internet access in Thailand?
What is mobile phone coverage like in Thailand?
What is the voltage in Thailand?