Micro lens? Are these like tiny things?
Nikon call thier Macro lenses "Micro", or at least they used to.
What sort of budget do you have?
Macro lenses usually start at about £250 for a dedicated lens - the SIgma 105mm gets some good reviews. Alternatively you could get some extension tubes - a full set will cost you about £75-90.
I bought a Macro lens a couple of months back and I have to say it was a very worthwhile investment - much more fun to use than tubes in my opinion.
Sounds like you've pretty much got your pick of the lineup around 100mm then.Lucky me , after Christmas i can afford to go up to £400