You don’t have to pay eBay anything to browse through items on its site. You don’t have to pay eBay anything to bid on an item. You don’t even have to pay eBay anything if you actually buy an item (although you will be paying the seller directly, of course). But if you’re listing an item for sale, you gotta pay.
Insertion fees (I prefer to call them listing fees) are what you pay every time you list an item for sale on eBay. These fees are based on the minimum bid or reserve price of the item listed. These fees are nonrefundable.
Final value fees (I prefer to call them selling fees, or commissions) are what you pay when an item is actually sold to a buyer. These fees are based on the item’s final selling price (the highest bid). If your item doesn’t sell, you aren’t charged a final value fee.
View eBay’s current fee structure at pages.ebay.com/help/sell/fees.html.