As it goes in a majority of Asia, you need to haggle for your prices.And I've learned there are different styles depending on where you are.
I grew up in a Taiwanese household. Haggling is a loud, competitive, sometimes even insulting sport. The players treat it almost as a competition, to see who can hold out longer. And whose bluffs to really call.
I learned really quickly it doesn't work in Thailand. Not when tourism is a major economy and not then the Thais maintain a culture of smiles. Instead, I recently finally discovered that silence is the biggest tool. Mixed with a little of Thai language attempts, the effect is far more, well, effective.
Me: *pointing* Thaw-rai? (how much?)
Merchant: An-ni... 150baht.
Me: *pretending to think* How about 60 baht?
Merchant: Mai dai. (can't do) 100 baht.
Me: *pretending to think*
Me: *pretending to consider*
Me: *pretending to calculate*
Me: *getting a bit ansty and trying not to show it*
Me: *resisting the urge to shift weight*
Me: *really contemplating either walking away or paying 100 baht*
Me: *just about to decide to-*
Merchant: *pats my forearm and lower her voice* OK. 50 baht.
Me: *whipping out the wallet with alacrity*