Where do I record my Cost of Goods for my eBay reselling business? TT defined inventory as "goods not sold". Do I record COG as business expenses?

It is entered in TurboTax in the Inventory/Cost of Goods Sold section where you enter your business expenses. When you work through that section, you will be asked to enter your beginning inventory (cost of goods on hand at beginning of year), ending inventory and purchases, labor costs, materials and supplies. The cost of goods sold is calculated by adding the cost of your beginning inventory to your purchases, labor and materials and then subtracting from that sum the value of the ending inventory.  Cost of goods sold is a business expense in that it is deductible from your sales, but it is technically not called a business expense, but is simply referred to as Cost of Goods Sold.