The Chatuchak Weekend Market is not a mall but more of a flea market just outside of Bangkok. You can reach the market which is open mainly on weekends via the MRT subway system as it is close to the MRT Kamphaeng Phet Station and the BTS Mo Chit Station in Bangkok. This is the largest outdoors flea market in Asia and has hundreds of stalls all selling different items. From cars parts to household goods, mobile phones and furniture.
If what you are looking for cannot be found in the shopping district of Bangkok then you certainly will find it here. The other options you do have are the Patpong night bazaar but those prices tend to be much higher than what you would find here. Patpong is mainly for tourists while you can get bulk items at the Chatuchak Weekend Market at Thai prices. There are a small number of hotels in the area if you are going to be spending time in the area.
The hotels include budget hotels such as the Nice Palace Hotel and the Lullaby Hotel or the better rated Mansion Sarasinee which is close to the market. Note that there is a small mall near the market called the JJ Mall which is a very small mall in the area. There is also the Jatujak Plaza next to the market.
Wednesday-Thursday (Plants & Flowers) 6.00 am – 6.00 pm. Friday (Wholesale day) 6.00 am – 6.00 pm. Saturday-Sunday (Miscellaneous) 6.00 am – 6.00 pm.