Let me say in advance I know very little about cameras which is why I've come here for help. I did try doing my own research via Google but frankly all the terminology left me pretty confused and with no idea how to really compare lenses.
Last year my wife bought a Nikon D90 with two lenses included - Nikkor VR 18-55mm and Nikkor VR 55-200mm. She's done great with those shooting landscapes and birds in trees, but lately she's been talking about wanting to do macro photography, especially insects, butterflies, flowers, that sort of thing (she's very much into nature photography, so I expect that fast focusing is going to be one priority).
I know she'd love to be able to take photos like the ones here, for example -- http://webdesignledger.com/inspirati...ro-photography -- epecially those shots with amazing depth of field.
With a budget of, say $1000-1500, what macro lens would be a good choice for her, and why? Links to photographs taken using that lens, and/or shops in Sydney that sell it, would be most appreciated.