Hum... I'm surprised that no one had commented about this. When purchasing valuable used products such as photography equipments, I often wonder if the product was stolen or not.
Reasoning in my mind generally is that if a product has its original box, most likely, it's not a stolen product. I mean, robbers just grab the products quickly. They don't go around and look for the boxes. Of course, there's no guarantee that a product with a box wasn't stolen neither. The robber could as well have purchased one of those empty boxes. Showing proof of its original purchase (invoice) is usually a good way to go.
Having said that, if the price for the same condition lens is outrageously more ($16 USD or more), I wouldn't spend on it. I would also avoid purchasing a product without its original box if I can. I hate to find out that I just encouraged a robber to steal more. Plus, the disappointment of the photographer that lost his/her valuable equipments would be forever in my mind every time I use the product as well. Certainly, I don't want to live with that guilt.