If you are on a tight budget I think the best value right now is a used
Nikon D200. You can find them on ebay for around $400 U.S. While there
is a small difference in image quality between the $400 D200 and the
$2700 D700, skilled use of the camera and production software like
Lightroom and Photoshop can make those differences disappear. You will
have to have a wider lens with the D200 because it has only a DX
sensor. Either that or take more rows of pictures. With PTGui doing
such an outstanding job of stitching these days taking more shots is not
that big of a deal.
Do you take a lot of pictures in caves? Street scenes in the dark? You
might need the high iso and low light low noise features of the D700 or
D300. If all you need is outstanding color, fast, sharp focus in an
ergonomically solid magnesium frame package that is sealed from the
weather and makes beautiful photos the D200 does it all for $400.
My D200 has truer color than 35 mm film and produces images that are
very hard to match with very expensive scanners and 35 mm film. Again,
the D200 can be had on ebay for around $400 if you get lucky. The
average price for one brand new is $830 and used $697. There are lots
of deals on outfits with assorted lenses too.
I keep looking at the D700 because it is the obvious upgrade camera from
the D200, but I am waiting until I go out on a shoot and get back and
say, "If only I had had a 700 I would have gotten that shot." That
hasn't happened yet, so if a D200 meets my needs, why blow $2700 on a
D700? Eventually they will be $400 on ebay too.