Henri Willig sells delicious Dutch cheeses. They have locations throughout Amsterdam with many of their slices available to sample. This location is near the flower market along one of the canals in central Amsterdam.
Be sure to try the smoked cheeses and the hot and spicy. The cheeses run around 10 euros for a 400-500 gram block. They also have some delicious Stroopwafels, which is another thing you gotta try while in the Netherlands!