What type of lens do you need if you want to do macro photography?

I'm thinking of taking an evening course at the local college in a couple of months and its for macro photography. I currently own a Nikon D60 with this lens:
http://www.henrys.ca/24039-NIKON-DX-VR-18-105-F3-5-5-6-AF-S-LENS.aspx

I'm just curious to know what type of lens I should be looking for and how much its going to set me back. The course is not being offered until Jan but want to know how much so I can plan ahead.

A Macro Lens
The cost will depend on where you go. You can find decent lenses online through a Web Search.

You need a true (1:1) macro lens - either the Nikon 60mm f2.8 or 105mm f2.8, or the Sigma equivalents (50mm f2.8, 105mm f2.8) which are cheaper.

The longer focal length macro you get, the greater the working distance will be between the end of the lens and the subject.

Lenses which are called macro that are 1:2 or 1:3 ratio are not true macro lenses.

They are actually called macro lenses and most major makers of camera systems make them

The lens you need for your Nikon D60 is the AF-S 60 mm f/2.8 macro lens.

http://www.nikonusa.com/...8G-ED.html

The NIkkor AF-S 18-105 mm is NOT a macro lens. What it is, is a nice wide angle to medium telephoto lens. Most people who are interested in having one lens to do most of their shooting are picking the Nikkor AF-S 18-200 mm (not a macro lens either) which give a much better range than the 18-105 mm as you can guess.

http://www.nikonusa.com/...IF-ED.html

So, you have to decide which lens you want first. A macro lens that is capable of shooting with a subject to image ratio of 1:1 or an extended zoom lens you can use for almost all the other subjects you tend to shoot

Most pros define a macro lens as being able to achieve a half life size magnification without extra help, the 18-105 falls short of this and is only a close focusing zoom, most "macro" zooms really are not macro since they can't pass this criteria. Nikon's older AF Micro (Nikon term for macro) Nikkors will not AF with the D60, this is not a real handicap since most macro work is done with manual focus but if you want something that can dual purpose you need to look at newer AF-s Micro-Nikkors or some of the 3rd party offerings by Sigma.

Well you could get a dedicated macro lens, but you don't have to. You could use extension tubes, or even a lens reversal ring to take macro shots.