Best Macro lens for the money (D3100 body)?

I have a D3100 and am looking to buy a macro lens without spending $800.So far I've looked at the:

85mm Nikon AF-S Micro
Nikon AF-D 105mm (used they sell cheaper than a new AF-S 60mm)
Nikon AI-S 105mm (cheapest used but looks like there's a metering issue with the D3100)
Sigma EX-DG 105mm

I started out thinking that a 60mm would be sufficient but have read a lot of reviews where people wish they had at least a 105mm. I also want to note that the subjects I want to shoot will be still (not really looking to capture bugs and such).

I would really like to keep it under $600 so that's why I'm exploring used options (assuming a used 105mm will be better than a new 60mm).

I've been happy with 60mm, but I admit a 105 would be nice sometimes. For ME, it's a matter of getting light into the mouth without shadows, but that might be an issue for you.

Samples:

Glance at the thumbnails and see if they look like the sort of shots you want to take.

OK.

1. The 85mm nikon. Personally I find it a bit on the expensive side. Build isn't the greatest but it does a fine job. Autofocusses on your camera.
2. Mighty fine lens, doesn't autofocus on your camera
3. No metering issue. It just doesn't meter, period. Also you need the PN-11 ring to get beyond 1:2 magnification
4. Fine lens, nothing bad about it except the price.

There's also a 5th option not on your list and that's the motorized version of tamron's 90mm f2.8

There's no optically bad macro lenses available any more. There's just very good and absolutely stunningly amazing. In general the 40 and 60mm nikon lenses would give you a significantly shorter working distance (16cm and 18.5cm as opposed to the whopping 31.5cm the 105mm does). Which means you have to get closer to get full 1:1 magnification. With bugs thast's very inconvenient, with other subjects it's no problem.

Additionally your Depth of Field gets really, really thin. I remember my very first teetering steps on the macro path. I shot this at f8 and ended up with a DoF of about 2mm. So often you'll find yourself stopping down quite a bit and that means bringing light, shooting from a tripod or both.