As previously mentioned, "gray market" equipment is product that is acquired by the seller through means other than use of the authorized importer. Camera manufacturers set local prices on their equipment based on a number of factors: local market conditions, rate of foreign exchange, the local overhead of the in-country sales and support staff along with their marketing costs. Give all of this it's easy to find great "deals" off-shore. Some US retailers take advantage of this and find wholesalers/retailers in other countries and purchases lots of product from them and then have it shipped to the US and then sell it at a price that undercuts the price of product acquired from the American subsidiary.
As mentioned, there has been an aggressive move by camera makers to "fight" gray market product as the problem has worsened. Too many people like to go to their local camera store, figure out what they want, and then go order the gray market version from B&H on-line to save some $$$. The fighting back consists of things like:
- Refusing to honor the equipment for warranty repair through the in-country service center. You may be able to get a warranty repair, but you may be told to ship the equipment back to Japan.
- Refusing to repair the equipment... period. Even for a price XYZ Co., USA won't touch it. Again, you'll be told to ship it back to Japan from a quote from them.
Nikon is firmly in this camp. The info on Canon is contradictory. Some reports indicate that Canon USA will except gray market warranty repairs, other reports I've seen say they won't. However, I did note that the reports that say they won't are generally more recent than the ones that they do. But without a doubt, the market trend is to try and push back the gray product.
To me, the possible hassle isn't worth the cost savings. If I need help with a product post-purchase, I sure as shooting ain't going to get much support from a mail-order outfit (either the legit NYC stores nor the Brooklyn "scam artists"). With US product, I can call the local support operation worry free. I've had Nikon USA fix two of my dSLRs free of charge out of warranty due to a known problem with earlier copies of the bodies. They were shipped there and back ASAP. There's no doubt in my mind my experience would have been not as pleasant if the bodies were "gray".