I no longer sell on ebay because of their money grabbing fees.
I sell all my stuff priced in the knowledge that they will get their fees. As said above, an auction house will typically charge 20%.
Then there is the large audience that go onto eBay to buy stuff to save trying to buy in town, or from a scrapyard, or plenty more reasons why people use eBay. I just bought some shorts today to save going shopping.