Buying a 650d/T4i... What lens?

Ok... I've decided after using allot of standard cameras and phones that I'm sick of the simplicity and lack of quality.. So I've done a bit of research and the 650d seems like a camera that will satisfy my requirements from a dslr (if you think there is a better one for me, I'm open for suggestions, my main goal is armature video and photography) I wanted a camera of which I could control the aperture, shutter and iso settings so I can get the shot how I want it.

I've heared from people that one of the big things in starting to make your work less amature and more professional equipment wise is lens's... Which is why I am asking.. For entry level video and photography (ide really like a lens which works nice with both) lens should I get for under about $400...

Thanks in advance and I hope to soon be uploading my photography in the near future on this board

edit:

oh and I plan to do nature/urban photography if that helps