Flea Market occurs every month, except August and December, on the 4th Sunday. From 6:00 am to 12:00 am neighbours are selling items in their houses and you can also sell items in your own house. Five of your neighbours will be outside and come into your house to buy. The rest will be in their house and waiting to sell things to you. During the day the neighbours inside and outside change roles, so it is possible to visit every of your neighbours to see what they are selling. Note: you cannot buy carpeting and wallpaper from your villagers.

To buy at a villager’s house, you only need to go into it and talk to your neighbor, who will tell you to look around. If you are interested in buying something talk to him again and then touch the item you want. However, they will not part with all items, if they do they will name the price of the item and you can decide whether you buy it or not. If you are lucky, this is a good way to get furniture or outfits you need to complete your catalog, sometimes you can even get some fossils, bugs, fish or gyroids for your collection. If your inventory is full or you don’t have enough bells with you, your neighbors will refuse to sell anything. After they have sold everything they wanted they will tell you that their shop is closed. Note that the price they ask you for an item depends on your relationship with them, if your relationship is really good they ask the same amount of bells for an item as Tom Nook would pay for it.

You can also sell your items in your house. There are some basic rules on how this works which you need to know first. You can only sell items in your main room (ground floor) and you can’t move, pick up or put down items if a villager is in your house, so the best thing is to set up the items you want to sell the day before Flea Market. But you can’t sell everything, villagers will only buy furniture, clothes and accessories that can be reordered from Nook’s catalogue (which includes downloadable content), fish, bugs, seashells and items from Phineas. They won’t buy fossils, gyroids, wallpaper, carpets or anything that can’t be reordered from Nook’s catalogue, like holiday items. All items have to be put on the floor, if placed on a table, they won’t buy it. Moreover, only five villagers will come into your house and each one will buy at most three items.

To sell things, you have to stay in your house and wait until a villager enters and starts walking through your room. Occasionally, they will stop and face an item, now it’s time to talk to them. If they are interested they will ask for the price and you can either enter the amount you want or tell them that this item is not for sale and the villager will continue walking around and looking for things. When you are selling the item, the villager may refuse to buy at that price but will give you the opportunity to lower your price, as often as you want or until you offer a price the villager is willing to pay. While villagers are looking at an item, it's also possible to push them to another item you wish to sell. After some time your neighbour will leave your house, normally they have bought three items before they leave, but sometimes it will happen that they stop buying things earlier or if you are unlucky they will leave without buying anything. You can force the villager to leave if you exit your house.

The price villagers are willing to pay depends on your relationship, the better it is, the more you can ask. But the absolute maximum they will pay is three times the amount Nook would pay for the item. But even the best relationship with a neighbour doesn't guarantee that they will pay the maximum. The best thing is to start with about three times the price Nook would pay (or something just below) and lower the price in steps of a few hundred bells.

To make Flea Market really profitable plan ahead and save some valuable fish or bugs (the ones Nook would pay 10,000 to 15,000 bells for), if you have no 15 fish or bugs, you can also take furniture you don’t need anymore or some seashells (especially pearl oysters and scallops). It’s also a good idea to check prices at Nook’s, so that you know how much you can ask for your items. Setting up your room in advance and making sure you have enough place in your pockets to hold all the money you will get, is recommended, too.

Make sure to check the Recycling Bin often, occasionally, you can find items that you have just sold to a villager inside, allowing you to sell the same item multiple times. Another possible way to get items to sell is to buy them from other villagers. This way, you can buy something for the same price as Nook would pay for it, and sell it for about three times that price.

Note that it is not possible to reset the amount of items bought buy a villager, by going upstairs into your attic and coming back downstairs unlike ACWW.