It is important, these days, for people who are buying DSLRs to realized that the camera bodies themselves are not the thing in which you want to invest the majority of your cash. Camera bodies come and go, and the rate by which this occurs seems to be going up and up, but there is one thing that is almost certainly a sure bet: lenses.
Lenses people bought twenty years ago, thirty years ago, are still not only valuable as pieces of camera gear, but also as actual financial investments. The Nikon 28mm f/1.4 sold new in 2006 for $1700, and now sells for well over $4000 on eBay.
So when you're trying to figure out what to spend your money on, spend it on lenses. Almost every camera body Nikon releases (and Canon, too, but who wants to buy those) these days is a top piece of kit, and will take fine photos for years and years. Unless you're fantastically rich, don't buy every new camera. Do buy all the fine lenses you can afford, though.