In
Bangkok , you can find reasonably priced and quality clothes in the popular Bangkok shopping areas. Few years back I did 2 weeks tour in
Thailand, but preferred to make shopping at Bangkok. I stayed at Bangkok for 6 days and made 2 suits and 4 shirts from one of the tailors around the Bangkok shopping area, even you can try with James Fashion, Moon River or Raja's International custom tailor. Also you can find hundreds of tailors around the major hotels and business areas like Surawong, Silom and Sukhumvit road. If you are looking for a specific material, then visit Pahurat textile market which has 100's of varieties. The Thai silk is very popular and good looking for making shirts or evening dresses, even I had 2 shirts. No trip to Thailand is complete without spending some money at Bangkok shopping centres, and even you can buy jewelry, shoes, bags and branded luxury goods. Hope this helps :)