Good external microphone for Nikon D5100?

Alright i need some sort of good but inexpensive external microphone for my Demetri, thats what i named my camera.preferably one that just connects to the top of it.sounding good is always a plus. But just can't be to expensive. Not yet.later i might buy a better one but i just need a start one for now.got any suggestions?

Look on Amazon.com, they have a lot, but most are expensive. The few cheap ones they have usually get the lowest feedback ratings because people have problems with them.