The local Farmers Market/Goods Market is near the Amazon river docks. If you see the pink dolphin statue, you are near by. Its a network of about 7 different streets that sell home goods, clothing, tools, fuits, vegs., meats and anything in between.
You can get some good tropical fruit at the fruit street then walk over to the meat street and be amazed at all the jungle meat sold. From huge 2 lbs. snails, to caymans, to exotic amazon fishes, to things I don't know what it was.
What to buy: I would caution anyone about buying any type of meat, even if its the mundane pork or chicken here since its an open air, out in the sun all day market full of flies.
I bought a selection of fresh fruits though and it was delicious. Especially the hard to find or exotic tropical fruits.
What to pay: 1 soles for a handful of starfruit = .25 cents.
cheap clothing if you need it.
In the southern neighborhood of Belen there is daily and active and interesting market for food, clothes and basic stuff. Not many souvenirs here, but I found it a busy place to stare at locals in their daily life.
After being at the zoo (se my tips about that), in the mosquito you will pass the Artisaneria Center (I am not 100% sure about the name). The driver will know.
What to buy: There are many things to buy att good prices. Textiles, wood carving, stones, leather etc.