So my 18 - 200lense broke any good suggestions for a macro lens
What is the size of the subject you intend to photograph and how close do you want to get to it?
I use macro lenses all the time to photograph different types of artwork for artists. I own Nikon's older manual focus 55mm, 105mm and 200 macro lenses and both versions of the 60mm autofocus macro.
I use the new 60mm AF G lens on a D700 and think it's terrific. On a APS size sensor camera it becomes a 90mm macro with the same close focusing ability. It's also about half the price of the 105 and 200 macro lenses. Sigma has a 150mm macro that's highly spoken of on the forums so that may be an option also, but I have no experience with it.
First I still shoot only film. That being said I am a great fan of the Nikkon 105mm AF VR ED lens. Give decent working distance and very sharp pictures.
You can probably save quite a bit of money and look for a used Nikkor 105mm AF ED and forget the VR version since VR is pretty much useless in macro photography. I always use a tripod and focusing rail for macro shots anyway.
In the interests of full disclosure I have the 55mm, 60mm AF, 105mm AF ED, 105mm AF ED VR, 200mm and 70-180mm micro lense from Nikon as well as the PB-6 bellows and extensions.