If this is something you need to do repeatedly, it might be worth using a separate browser with an ad blocker add-on installed, then use the element hiding tool of the ad blocker to hide whichever sponsored listings or other page elements you do not want, and then print or save what is left.
Once you have set that up so that only the listing is shown, you should be able to use that browser any time you want to print, and the listing should be in the format you want -- unless eBay changes how pages are formatted or includes extra sponsored listings.
