Check out the department stores for prices, figure to pay a third to a half when buying from the stalls. If the heat, pollution and over-charging becomes too much, head for the shopping malls. These are all over the place in Bangkok. A huge, multi-storey shopper's paradise, best described as a street market laid out on five floors with a hotel at one end and a department store at the other. The main kick is prices almost as low as the street markets without the dreadful heat.
Some bargaining is necessary.
The quality of gold does vary somewhat, the good gold shops having an excess of local customers. It doesn't really get going until after eleven in the morning. Across the road from Mabookong is Siam Square with some good book and record shops and somewhat expensive clothes stalls but some nice lines that you don't find elsewhere. Wander around here, then skip over to Siam Centre , good for the more expensive clothes, Tower Records, Boots, Body Shop, etc. Next door is Discovery Centre , a huge range of designer clothes stores, often with heavy discounts.