Advertising is a separate fee to the actual sale you agree to the terms when you use promoted listings. I get lots of sales from sponsored promoted listings and only set the ad rate at 2%. At the end of the day its a minor fee at that selected rate. You have to compete these days for your new buyers to get your items seen first by the algorithm. Personal choice if you don't like promoted listings but many sellers including me use it to get the extra sales. Most business pay for advertising I see it as a plus that ebay will push your promoted sponsored listings to get more sales for you.
