well how much you wanna spend?
that will be be a big decision makers. guessing from the camera i'm going to go out on a limb and say not a ton. if it was me i would look at the sigma and the nikkor lens. usually can find a good deal on the bay.
the only Sigma macro lens that will offer true macro and aurofocus on that body is the 150mm and 180mm..they are 530-600 in price.
the only Nikon one is the 100mm VR and I believe thats like 800
If you want a good lens but its not true macro but it gives a pretty darn good close up of a 1:2.3 magnification
The sigma 17-70
Sigma added the HSM(Hypersonic focus) to this lens to be used with the D40 series since it does not use the