+1 here for the Nikkor 105 Macro Lens.
I thought about renting it with some other macro lens's but that could be money spent on the new lens itself.
Take the plundge!
It's well worth it, as long as you have a lot corals,insects and such you want to take pictures of.
With the 105mm I can be as far as 8" and still get a great macro shot.
If you think $800 is steep, I bought mine for $1000 a while back...$800 is a steal.