You pay for listing items on ETSY. Depending on your "level" of your subscription on eBay, you get the first 50-200 listings free (but you pay a fee up front for listing that higher number of items) but pay when something sells. Each time an item sells, regardless of site, the payment will have about 3.5% taken out as a transaction fee, just like credit card companies do. You pay this fee, not the buyer. It is probably a wash as to which site is more expensive. They simply make their money in a different way. I will tell you that dealing with eBay sucks. They don't care a thing about the businesses/people listing their items. ETSY is more user friendly. Unfortunately, eBay has more exposure, simply because of their size.
