When you want to make the most money with your auction. Generally, this is when there’s a big demand for product or an item that’s unique or hard to find. You may also want to buy low and sell high if you know that other people are willing to pay more than what it costed you (i.e., used car salesmen). Also consider auctions like eBay Live where the items are sold simultaneously across multiple locations in different countries. There are other great sites out there but I tend not to use them because of their lack of transparency; so many variables!