Chatuchak weekend market.
Its big. Really big.
You can find anything and everything here, but shops seem to be reluctant to negotiate much on prices.
Also, there is surprisingly good food that can be found here.
Don'to be intimidated by long lines and limited seating, as these are often the best places to eat.
Dishes are served incredibly fast, often your order is placed before a seat is found for you.
They usually offer only a few menu items, keeping turnover high.