At blk 651, Juronhg west st 61, next to Pioneer MRT, there is this medical hall known as Kim Sang Medical hall which sells cheaper milk powder and diapers
E.g.
Mamil Gold 700g-> $26.50
Mamil Step 2 700g-> $24
For Mamil Step 3 700g-> 2 bottles at $37
Mamy Poko
S(48 pcs), M (44pcs), L(38pcs),XL(34pcs) -> $15.50
You can contact them at 67693307, 91711077,96499269 for other brands pricing.
Happy shopping =)