Your best bet is to try a set of close-up adaptors at this point. Hoya HMCs are good, and would run about $80 for a set. Down the road, if you really get into it, you can buy a Nikkor 60mm 2.8 micro lens and a 2x telconverter. This is what I use for insect macro photography, and the max
sync-speed of my N-80s match up well with this focal length. The 105 Nikkor micro is also really good.

--Jeff