It's a bit more expensive than selling on Amazon, depending on the item.
Looking for certain used electronics (recently music synth stuff, in the past vintage test equipment), I tend to have to select a lot of filtering options: "North american sellers only", "Condition: Used", etc.
So if your search is ordered by price, it will show their listing first when in reality, the actual item you're looking for is much more expensive.
I have no idea why ebay allows this to happen.
Ebay doesn't show the lowest-price option by default; its default is "best match", whateverTF that is. You have to explicitly choose "lowest price + shipping". I'm in the habit of always doing this, and generally researching things to death when buying online to make sure I get the best deal, but I know I'm not a normal shopper. Most people just see something that looks good and click on it and buy it.