Macro reverse ring for nikkor 18-55?
Wich one should i buy?
You may use any macro reverse ring.
A place to read people's stories and stuff too would be nice.
Depends on your Nikon model, not all Nikon DSLR cameras allow you to take a picture if the camera can't determine the aperture.
With the kit lens reversed on the camera you have no means of altering the aperture, when your very close to the subject you will have a tiny depth of field, to widen it you need to use smaller apertures (higher f number), better to use most any older lens (loads on eBay cheap) then you can alter aperture on the lens. You will need a reversing ring from Nikon bayonet mount to whatever the filter thread size of the lens is.
There are better ways to get close to the subject, extension tubes or bellows allow for any degree of magnification bordering on microscopy.
When using any of these including reversing rings shutter times will be long, small area of subject reflecting light into the camera, the small aperture required to get a working DOF all contribute to a dim image in the viewfinder focusing is a problem. If you camera has live view use it.
Don't forget, with a reversing ring there are other things to deal with for macro photography…
but there are loads of places for reversing rings.
I've had good results with Photodiox brand in the past.
Reversal rings are simple one-piece assemblies that are easy to manufacture.
EDIT:
Here you go, I used photodiox reversal rings similar to this, only mine was made for Canon mount. It was a perfect fit, you probably won't have any problems with the Nikon adapter either.