Hi!
I recommend you head down to Sim Lim Tower (don't confuse it with Sim Lim Square, which is IT related and directly opposite SIm Lim Tower) on Jalan Besar. Not far from Lavender. Nearest MRT is Bugis or Little India.
Don't expect modern stuff there though, it feels like it is stuck in the 80ies. Lots of measurement stuff though.
happy shopping, Werner