You can try Journey East at Tan Boon Liat building (Outram/Tiong Bahru). They sell a good range of restored European-inspired Mid-century teak furniture from Art Deco and Retro periods. I've been to a few Vintage and Retro shops, and I like the selection as well as the level of craftsmanship here better.
my friend was able to buy a few vintage furniture from Journey East It's located at Tan Boon Liat Building, Outram Road. Or you can call them at 65 6473 1693
Antique and vintage furniture is the collecting area that has been least impacted by the online world. You will get most of the designer and expensive and cheap furniture in the online stores.