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Fixed Price listings (not auctions) will allow setting up a listing with a quantity of more than one. Just list the number of items available and set the price for a single item. The buyer can then chose to purchase one or more. However, you may need to pay attention to the shipping costs. Sometimes multiple items can fit into the same box for the same shipping cost. But if they don't, then you may need to create a shipping rule that will apply quantity shipping.
