At the moment I am using a reversing ring with some old Miranda lenses (for Olympus OM10) and i managed to photograph this: http://500px.com/photo/83276997/red-beetle-by-lewis-charlton?from=user_library
The picture is ok but as you can see its not in great detail.
So i want to get a decent Macro lens for my D5100 that is not overly expensive and can take pictures like this: http://500px.com/photo/80793981/the-eye-by-bug-eye-)?from=user
Thanks
Read more: Good macro lens for Nikon D5100?