Brown Rice Paradise
A good place to get gluten free/wheat free/dairy free food items ranging from flour, sauces, snacks, pasta, cereals, canned food and organic personal/household/baby products. They have one shop in town (Tanglin Mall) and a smaller one in the East (Siglap).
Four Seasons Organic Market
I have only been to the one at Marine Parade. They stock some items that I don’t find in other places (like Eden Food items). The shop is smaller than Brown Rice at Tanglin but it’s worth checking out.
Fairprice Finest Organic Section
Some stores may offer more varieties than others. Eg. The one at Parkway Parade has a separate section with more options than Bishan’s store.
iHerb
You can get all kinds of products from here. Check it out yourself and use the coupon TLS586 to get $10 off your 1st purchase above $40 or $5 off below $40.
Howard Storage World
Plenty of storage containers to choose from. Browse the catalogue and read their organising tips for ideas. I especially love their pantry storage ideas!