Animal Crossing: New Horizons now has its own dedicated online store for buying and selling in-game items for Bells, not to mention bartering items.
It's called Nookazon, courtesy of the web-savvy Daniel Luu (AKA Squishguin), and once you know how to use it, it can be an invaluable tool for building your dream island or fattening your wallet. So, we've put together a quick primer on what Nookazon is and how it works.
Nookazon allows users to sell or trade almost anything in the game. There are categories for clothing, recipes, flowers, fossils, fruits, furniture, materials, posters, songs, tools, and even villagers, who can be recruited by visitors once the host convinces them to leave their island. Once you make a free account, you can peruse these categories for appealing offers or search for specific items individually.
Once you find a listing that interests you, you'll need to contact the seller. At the moment, this must be done through Discord, but Luu says he's looking into adding a chat function to the site. For now, you'll need to add and message sellers on Discord in order to arrange an in-game meetup. You bring the specified items or bells, they bring the item, you make the transaction, and go on your merry way.
If you want to sell an item through Nookazon, you'll just need to add a listing to an item's results. Enter your price in Bells, add any items you might be interested in trading for, and submit your listing. Once you receive an offer, it's back to arranging the in-game transaction.
That's how everything would work in an ideal world, but as Luu points out on Nookazon's FAQ, there are plenty of ways for things to go wrong. There's an obvious risk of being scammed, and people may grief sellers under the guise of prospective buyers. Apart from following the usual Animal Crossing: New Horizons multiplayer guidelines, you can help prevent and mitigate these issues by restricting access to certain areas of your island, contacting Nookazon Discord mods if things go awry, and being careful with what information you share over Discord. Basically, imagine you're using eBay or Craigslist and take similar precautions when applicable.