Are there any good nikon zoom lenses with wide aperture openings for about $300?

I have a nikon D3100 and a standard zoom lens with an f5 aperture, so I can't take good pictures in low light, so I need a new one. Can anyone help me out?

Will the auto-focus WORK?

I own a Nikon D60 and I'm thinking of getting the 50mm 1.8 AF, but I don't know if the AF will work?

Do Tamron make an 18-200mm lens that would auto focus with my Nikon D3100?

Do Tamron make an 18-200mm lens that would auto focus with my Nikon D3100?

What teleconverter fits the Nikon D40?

Looking for a teleconverter for my Nikon D40. Which ones will work for it?

How to do these type of photos with a nikon d3000?

Thanks!

Lens for Nikon D5000 with 200mm or 300mm max reach?

I'm looking to get a new lens and have looked at the tamron 70-200mm which looks quite good but I already have a 55-200mm which works well and am looking for something with a little more reach.
Any suggestion apart from 70-300mm (just don't like them).

Black window, focussing problem with teleconverter lens for Nikon D3100?

I recently bought a Nikon D3100 and a 2X teleconverter lens along with it.
The standard kit provided with the camera was a 18-55 mm VR.
When I bought it, I didn't really know what a teleconverter does except for increasing the zoom capabilities.

Now that I use it, I'm facing two difficulties, and I'm not sure whether these are problems with the lens or whether this is normal.

1) When it's on 18mm (zoomed out), the photographs taken appear through a circular black window.

2) As I approach 55 mm such that the window disappears, any photographs I take are focussed only on the subject in the centre while the surrounding areas are blurred.

Kindly tell me whether this is normal or should I get the problem clarified with the dealer.

Is usagoodselling.com legit?

I'm considering buying a Nikon D3100 off the website usagoodselling.com. I just want to know that before I buy the camera, that the website is legitimate. Has anyone ever bought anything off of this site?

How to do macro Photography with Nikon D60?

I bought the extension tubes and i have the screw on lenses 1+ 2+ 4+ 10+ I have the 18 to 55mm vr lens I have no idea how to set it up or exactly what to do can anyone help on what i'm suppose to exactly do?

Where to get a lens adapter?

I have a Nikon D3100 and my grandpa has an old Nikon camera and a bunch of lenses for it. I was wondering if anyone knew where to get a lens adapter for my camera so I could use the old lenses. If anyone could post a link to a website that sells them or even on the Nikon website if they have them, because if they do, I can't find them.