I am also weighing my options for a Macro lens, but I needed a point and shoot more than anything and spent my money on a Sony RX100 which I got today. Fantastic little camera with a huge sensor 1.8!
Anyway, while looking at my options, I ran across the typical lenses by Sigma and Tokina which offer a MACRO mode. The prices of these lenes were in the $170-$199 range. Although, it is not a true macro lens, it does have a macro mode and if you do not already have a zoom, this may be something you are looking for. They are not fast lenses though.
Ideally, when I do buy, I plan to get the 105DC.. or something FX, I have an D7000 but half my glass are FX lenses. I anticipate moving to Full Frame soon. The reach on my FX 24-300mm on my D7000 Crop is insane.
I thought the sensor size on the RX100 is 1" same as the sensor size on the Nikon 1?
Earlier this year, I acquired a wide angle Sigma lens for my D90. I wanted to take that to Europe with me instead of the 17-55mm because the latter is big and heavy. But, after taking some test shots, the Sigma went back. And, that lens was supposed to be a "sharp" example of Sigma optics. Maybe I got a bad one. But, I am a bit more hesitant to get another Sigma/Tokina now.
I was reading about the 105DC this morning too.