I usually buy my cloths from Marty's New Fashion at 178/1 Sukhumvit Road, Between Soi 8 and 10. It is a family run shop that was opened up more than 40 years ago (maybe back as far as the Vietnam war) at that location (before all the madness). It is run by two brothers (I have not seen the father there for a while so I am guessing he is retired). The cloths are well made and will last a very long time. I don't think they use a factory (though they use a seamstress somewhere nearby I think), all the material that they use to make it is sold in shop (and I seem to remember them going on business trips to find quality material). Usually they like to have you come back for a second fitting to make fine adjustments (after the first fitting and initial tailoring) -- though most times I have not needed further find adjustments.