Keep in mind some larger sellers advertise/list on eBay and Amazon and other markets. Cross listing is not uncommon in online trade and you wouldn't really expect individual shipping based on the market order.

In a galaxy far far away in eBay Australia's infancy , I had a BMX for sale on Sold.com (remember the Yahoo site that eBay bought), the Trading Post at the same time and I also threw in eBay as an afterthought . Mind you I had 5 of the same one and wanted to maximise my exposure to selling them as quick as possible.