what's a good macro lens for flowers/insects?

[nocents]

I'm considering buying a 30D and would like a macro lens for taking photos of flowers and insects. What's a good macro lens for that? I would ideally like to spend under $500.

[RichNY]

http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=194451&is=USA&addedTroughType=search

[coldrain]

There are quite a number of good macro lenses.
With insects you want it to be a bit longr in focal lenght, to be able to keep a bit more distance.

Cheapest but VERY good macro lens:

Sigma 50mm f2.8 DG.

For Canon only (since you also ask this in the Nikon forum): EF-S 60mm f2.8 USM. Sharp, fast and silent focussing.
For Nikon only: Nikkor 60mm f2.8. Best Nikon macro.

Sigma 70mm f2.8. Very sharp and good macro lens.

Now the 100mm class, which will allow a bit more distance to the subject.
3 are "best", on 3 platforms.
The Pentax 100mm macro, very sharp. Pentax only, might just fit into your budget.
Canon EF 100mm f2.8, fast and silent AF, does not extend at all, sharp and contasty, very nice lens. Canon only, may just fit your budget.
Tamron 90mm f2.8. Very good manual focus feel. Very sharp and good contrast. Will fit your budget, on all 3 mounts available.

The Nikon 105mm f2.8 and 105mm f2.8 VR lag the competition (including the Tokina 100mm and Sigma 105mm f2.8) in resolving power and contrast. Both also are way above your projected $500.

The longer 180mm f3.5 lenses are all way above your budget.

[achuang]

Since you asked this in the nikon forum also, I thought I'd just answer it here. I have a Nikon 60mm f/2.8 macro lens and it's very sharp and a good length for flowers but not long enough for shooting insects due to the short working distance.