Good 18-55mm lens for nikon d5000?

A good lens for nikon d5000 which is better than the standard stock one which comes with the camera? I mean quality wise, sharpness and contrast etc.

nothing which is really expensive.

There are several replacement lenses in the same general range. Tamron 17-50 f/2.8, Sigma 18-50 f/2.8, Nikon 16-80… The starting price is about $500 for these.

To get a major improvement in quality for less money, you'd be looking at a prime lens like the 50mm f/1.8 or a 35mm f/2.

You can get more versatility with sharpness as good as or maybe a little bit better with te 18-105mm AF-S VR. It's about $400.

You're not going to be able to do any better unless you go far higher in cost.
I have the Nikon 18-55mm VR lens. I've had photos published in local newspapers using this lens, so it can't be that bad.