There seem to be many lenses being sold on Ebay as "NEW" by individuals who buy a kit and then sell off the lens since they do not want or need it.
I have a customer who bought a Canon 24-105mm F4L lens this way last month for $750, a pretty good bargain, and it had the USA warranty card with it. She filled out the warranty card and submitted it to Canon.
10 days ago the AF quit working in the lens, I even tried it on two of my bodies and it would not AF so she sent it in to Canon for repairs. Today she got an email from Canon that the AF drive motor needed to be replaced and it would cost $385. They would proceed with repairs when she authorized them and made full payment. She called Canon, in my presence, to protest the charge and try to get it repaired under the warranty as registered. Canons response was that the warranty is valid only to the original purchaser and that her "receipt" from an unauthorized retailer (an individual) constituted a "resale" and voided the factory warranty. She is stuck for the repair costs, or Canon will return the lens to her as-is at their expense should she decide not to have it repaired.
Bottom line here is, learn the lesson, there are no great "bargains" to be had on Ebay by buying a NEW item from one of the hundreds of unauthorized resellers listing "new" bodies or lenses there. If the item was not purchased through an authorized retailer in the USA, you simply have NO WARRANTY to fall back on. My customer is now having the lens repaired at her expense and she will now have more money in that lens than if she had bought it new through any retailer in the country, even if she had bought direct from Canon, and she still will have no warranty on the lens.
Trying to save a few bucks on quality camera gear will pretty much always cost you more than if you bit the bullet and bought the new product from a proper source.
Just a friendly warning for anyone out there on UHH looking at some of these "bargains" they may find on Ebay. There are authorized retailers using Ebay, such as Adorama, Cameta, Roberts and KEH, but there are a LOT more that are not authorized retailers. Beware.

Also, there are a lot of retailers on Ebay that state they are "authorized", but are selling grey market. Same caution here.