So, I walked into Best Buy to pick up a USB drive yesterday and walked by the open box section. I happened to see a Canon lens box sitting there. I walked over and saw it was a 17-40 f/4 L. They had a price of $649 on it. The box looked good and wasn't beat up. The tag said all items were in the box, nothing was missing. I have been looking for a lens in that range but hadn't yet gotten serious about buying. I asked an employee if her knew anything about it, whether it was a return or a floor model. He said it definitely wasn't a floor model. He said someone had probably bought it from them online and returned it to the store. He also said there was also 10 percent off that price making it $584.10. With tax here it came to $624.99. He asked if I wanted him to open it. We took it up front and he removed the security device from it. Everything was packed as if it just came from the factory. The lens looked perfect. I removed the end cap and the lens cap. It all looked good except two spots on the front element. I had a lens cloth with me and asked if he minded if I cleaned it. He said I could and both spots came right off. IT was perfect. I couldn't pass it up. I figured I could sell it for at least as much as I paid for it or simply return it to Best Buy. He said I could return it if I wanted.
Well, I took it home, attached it to the camera and it works perfectly. The focus even seems to be spot on with no MA. I really hadn't planned on spending the money yesterday but I'm glad I happened upon it.