After the new, massive lawsuit against
B&H Photo, I have decided to never again link to any item they offer for sale. Instead, I will recommend other retail outlets, like BestBuy.
Tamron - SP 24-70mm f/2.8 Di VC USD Standard Zoom Lens for Nikon - Black
I just looked, the 24-70 VC from some of the big gray-market retailers is more in the $800 range. DO a search on gray market goods, for more information. Gray market goods are the same construction grade as the officially-imported items, but were brought into the USA outside of "official channels"; one thing that gray market good offer the customer is a lower retail price--AND a good sales lever for a sharp salesman to sell you an extended warranty.
Like most types of 'insurance', a $150 to $199 warranty sold by the retailer is a MASSIVE PROFIT center. I used to sell photo/video goods...salesmen receive HUGE
spiffs (sales incentives, payed to the salesman) for selling a warranty, which in 95% of cases, will never be needed, and which is basically, 95% pure profit to the retailer.
If a lens has a manufacturer's 5- or 6-year warranty, then the salesman has almost zero chance of selling a $159 extended warranty, for which he will likely receive anywhere from 15 to 25% of the sale price in his paycheck.