Check this link, Tamizh ..
Good tailor around Bangalore
In Commercial St. Bangalore, most of them are authentic and good.. Though I cannot vouch for any since I havent personally made one from them.. I used to give my blouses to a guy in Rajajinagar 1st Block. He is good and gives the design you want.. I like people who can interact and throws some ideas instead of just nodding heads.. So, liked this one.
Also, there is a place in Indiranagar where my friend used to get her blouses stiched.. Those were more modern and I dont think he could stich anything traditional.. ;) Or maybe my friend had all of hers stitched that way ! :) I dont remember the address though.. Can get you if you are particular about such blouses..