Ideal Nikkor Micro Lens?

I have a budget of about $650 and I have a Nikon D5100.

I currently use my kit lens and it gives nice results for Macros if I edge near it's 10 inch focus point. Although, I have to be spot on at that 10 inch point for good shots and even then, I have to use Lightroom to sharpen further. I don't like relying on Lightroom for sharpening.

I want to be as close as I can. What Nikkor Micro lens do you recommend?

Added (1). Thank you so much AWboater! You've cleared up a lot for me! I'm looking at the 40mm you suggesting and I'm really digging the price, but I also found an 85mm lens.
http://www.nikonusa.com/...ED-VR.html
I'm really liking the sample pics. Is it worth the jump in price for the increased focal length?
I'm debating between the 40mm you mentioned and the 85mm.

Nikon has 10 different micro lenses. Which one is for you depends on your budget, type of macro you want to do, and so on.

The shorter micro lenses, like the 40mm lens requires you to get a lot closer than say the 105mm lens.

However, the DoF is often an issue with macro. At 40mm, the DoF will be greater than a 105mm lens.

So, the tradeoff is that the 40mm lens offers a wider DoF, but at the expense of having to be exceedingly close. The 105mm lens allows you to back up a bit (useful to keep from scaring off bugs), but the DoF is much more narrow.

The DoF at 105mm is sometimes wafer-thin, so you just about have to have the lens perpendicular to the object for any kind of DoF. And often, you need to use a small aperture to help a greater DoF. This can also present a problem as micro lenses are often capable of f/32 to f/64, and that may require a tripod and/or flash - even in daylight.

In contrast, a 40mm micro has a much wider DoF, so you can use it at an angle to the subject other than perpendicular, and can also use larger apertures, so you will not likely need a flash.

So there are in reality different purposes for the different focal lengths.

I'm into macro big-time, and I own both a Nikon 40mm micro and Tokina 100mm macro lens, as well as Nikon R1 macro flash, tripod, remote release, etc.

If I shoot bugs, I will usually use the 100mm Tokina. For macro photography of inanimate objects, I prefer the 40mm micro.