If you like vintage design furniture you should really check out Neef Louis. You will find Neef Louis at the North side of Amsterdam (where you will also find Noorderlicht , The Ijhallen, and Pllek). So even though it is quite a journey to the North, it is worth it!
Neef Louis is a gigantic place and it’s absolutely stuffed with all kinds of old, vintage and design furniture. I would really love to be able to buy just all of it! Unfortunately my budget doesn’t allow me to do so. But still, I love to look around and it gives me inspiration.
Across the road you will find Van Dijk & Co which is much the same but with more classical types of furniture. Also worth a look!