You'd need a 1:1 ratio lens...
I believe these are...
tamron 90mm
nikkor 105mm micro (d version may be in your budget
second hand)
sigma 105mm
sigma 150mm
You probably wont be able to af (no motor in your body) but with macro you will probably be using manual anyway.
You will possibly need a flash and maybe some tubes to get closer..!
I have the 105mm nikkor micro - pics in links in sig. I can say its a brilliant lens. Oh and if the f# won't go to 2.8 its to do with the focal distance, so don't worry about it

You'll poss be shooting around f8 anyway