Newbie

[jr211]

Hello,
I just bought a "new to me" Nikon D90 with the 18-105mm kit lens. I'm excited to learn more about photography.
One of the areas that fascinates me is macro or closeup photography. I realize that the kit lens can't focus at very close range.
Can anyone recommend a good quality macro lens (that won't break the bank)? Also, how well do lens extensions work? The price is very attractive (Ebay has a 0.45x macro and 2.0x telephoto for $23) but not sure about the results.
Thanks in advance.

[Biomech]

Don't get confused between a macro lens and a closeup filter. There are alot of filters on ebay that just screw on - I tried them out once and they were aweful. I think my next lens will be a 100mm macro (as someone recently mentioned) to replace my 30mm macro - so I'd say that. Not being a Nikon man, I'm not sure what they have to offer but someone here will