Selling something doesn’t seem that hard. You take your item, list a price that works for you and see who is interested. Maybe you adjust the price to fit the market better. Perhaps someone tries to haggle, after all, in some countries that is always expected. Then you see demands that you give it for free. Or a trade offer for a broken, used car that is less than a third of the value of your item. 75$ for a 250$ smartphone.