Well, this is what I have - the D2X, but if that was your budget, I would go for...
Nikon D200
Nikon lenses: 50 mm/1.4 (around $300),
85mm/1.4 (around $300), 28-70/2.8 (around $1,400) and 70-200/2.8 (around $1,400)
Now I have all these lenses with the D2X, so I can honestly say, they rock!

I also have the Sigma 105/2.8 macro and Sigma 10-20 super wide angle, but even though I think they are great to have for my nature stuff, I don't use them as often as the others.
I don't use flash, I don't use filters, I do use a monopod though with the 70-200 when I shoot sports