Just my opinion, but I wouldn't. You can save a chunk of money, but if you have a problem with the camera, it will become a headache to get it serviced.
Nikon USA will not service a gray market camera body or lens if it breaks - you would have to send it to Japan. Not only will they not cover a gray market item under warranty, they won't repair it even if you offer to pay for the repair.
As John M notes above, local camera repair people may be able to repair a lens. The type of repair John had done on his lens is something that any competent camera repair person should be able to handle. A digital body may need to go back to the manufacturer, depending on what the problem is.