You can get a discount, but it involves lots of hoops and targets.
IIRC the biggest discount band was 30%, however that was when I last qualified for any discount, but they’ve since changed the seller panel so you can only see the next discount band you can achieve, which for me would be 15% if I could meet their new dispatch requirements.
Over the past year, they’ve been changing things to have similar requirements to Amazon’s Marketplace, however I’ve got no idea how the costs compare as I’ve never looked.
I know quite a lot of sellers who price things more expensive on eBay than on their own websites, then ensure they have suitable mentions of thier own website. Ebay’s big advantage is it opens up a huge buyer base, however it comes at a cost, but that cost is still alot cheaper than if you had to pay someone to build/maintain a website.
I’m sure a google search should turn up the current discounts along with requirements.