Normally, I sort eBay search results by price+shipping, lowest to highest. However, sometimes there are some sellers who are selling only one of the item, whereas others are selling it in a pack of two or four. The pack of four might be a better price per item, but it isn't going to show up on the first page of my search results.
I'd like eBay to provide the option of sorting search results by price+shipping per unit. So if widgets cost $2 each (including shipping), but a lot of four widgets costs $7, the $7 lot of four will appear above the $2 single widgets.