There are pluses and minuses to buying refurbished cameras and lenses. Generally you will save money. Refurbished cameras have been originally sold and returned to Nikon with a problem. The problem may have been very minor or more serious - you don't know. The problem cameras are repaired and tested by Nikon Repair, and made available through a variety of channels for sale. Refurbished gear normally comes with a shorter warranty. You can often purchase an extended warranty - but I'm not sure it is worth the expense.
Pricing on refurbished gear varies - sometimes it is only slightly below the cost of new gear. Other times it offers substantial discounts. I recently bought a refurbished Nikon Fieldscope at 50% off MSRP. But it has no electronics.
Problems with new cameras are rare, but they do occur. Problems with refurbished cameras occur at about the same rate. Most problems show up in the first 30 days, so if you are able to get out and use your camera you can give it a good test.
The checklist for a used DSLR is a good place to start. With lenses, problems most frequently are with VR or AF - both of which are easily repaired. We don't have much data on life expectancy of VR systems so for lenses, a five year guaranty associated with new gear is useful.
I would readily try to save money by buying a refurbished camera or even a used camera if I was looking at a D300/D300s, D700, or D3/D3s. Since they are at the end of the model cycle, new cameras will depreciate immediately to market value for like new used gear. KEH.com is a good point of reference.