i am not sure I like the idea of zoom connected to your DSLR. Firstly, zoom mic is not a shotgun mic and will pickup all kinds of sounds around you. 2ndly, it doesn’t mount on your camera, therefore, it can be dropped, etc.
i think the best solution is a mid-range priced mic. rodes are very expensive and not worth the price in my opinion.
i would recommend:
BRONSTEIN BRN-200
https://www.amazon.com/BRONSTEIN-Video-Condenser-Microphone-Mount/dp/B00ATUM4DW/ref=sr_1_1?ie=UTF8&qid=1369963278&sr=8-1&keywords=dslr+microphone+bronstein
AUDIO TECHNICA PRO24CM
https://www.amazon.com/Audio-Technica-PRO24CM-Stereo-Microphone-Camera/dp/B0016ARZ9C/ref=sr_1_10?ie=UTF8&qid=1369963336&sr=8-10&keywords=dslr+microphone