This is a suggestion, not a recommendation. It's given in the spirit of giving you something to compare against (smart shopper style).

From the November 13 issue of The Straits Times, Urban section (weekly tabloid pullout in our main newspaper here, this pullout focuses on fashion):

"Bespoke (ie custom) menware, from $130, from Clothesmith: A personal consultation at this funky tailoring service can take as little 15 minutes... It usually takes about two weeks for your order to be completed, but overseas delivery is available".

Address: 48A Boat Quay (sorry, phone number not given).

This location is close to the financial district; Boat Quay itself is an expat hangout so I reckon they should be good with tourists.

Again, I don't vouch for them - just offering another suggestion. Probably best if you make your way to the shop, look around and make up your own mind. Good luck!