Getting in to a Nikon DSLR with closeup question

[jgamble]

I am planning to buy a Nikon D80 with 18-135 kit lense and a Nikkor 70-300. I take a lot of wildlife and nature shots. I need some advise on what I need to take closeup pictures of insects. I like to be 2-3 ft away if possible. I don't know whether it is better to go macro lense, extension tubes or closeup lense. If the lenses above are bad choices, give me some better ones. I am trying to keep the entire purchase under $2000. Thanks in advance.

[SpecialK]

If you want to be that far away you need a long lens that focuses closely.

This may help.

http://www.amazon.com/Sigma-150mm-Ma...e=UTF8&s=photo

I do not know the image quality of this lens but 2 of my 3 lenses are Sigma and I like them well enough.

[wh0128]

also Nikon does have some long telephoto lenses like the 200mm f/4D ED-IF AF Micro-Nikkor but that is quite spendy. I think that 150mm f/2.8 from Sigma should do you some good with insect photography.