Dappermarkt
Dappermarkt basically sells everything, from clothes to food, and other daily necessities. If you just want to spend 3 or 4 euros to eat something delicious, you can come and have a look. However, don't expect the clothes to be of big brands, as they are very cheap, but very unique. This is indeed a good place to buy cheap vegetables and fruits. There are also nice cafes around. It can be considered one of the top markets in Amsterdam.
Noordermarkt in Amsterdam
The Noordermarkt on Saturdays is quite nice; it's a market that focuses on organic produce. I like to buy some delicious food here, and there are also some other small shops. If you want to buy more books, clothes, etc., come and browse on Monday.
Albert Cuyp Market
Albert Cuypmarkt is a market that everyone really likes. Besides eating (which is very important), you can also buy various trinkets and cheap clothes, around 2 euros, which are quite good. You can find some local specialty clothing that is quite fashionable.
Westermarkt
If you like trendy clothes and such, you definitely can't miss the Westerstraat Market! Every Monday, you might find some nice clothes, and maybe even some good brands!
Postzegelmarkt
Postzegelmarkt is recommended for niche collectors, mainly stamp, coin, and badge enthusiasts. It is a relatively small market. However, there are also many collectible shops around this street, which are worth visiting.