Basic add-on microphone?

[ajf]

I have a Canon 600D and have been using a bit more for various video clips.
Noticed the sound tends to be very 'muddy' and mixed.

What would be a reasonable add-on microphone without spending too much?
Guessing something directional would be better?

Then again are there in camera settings I should look at?

 

[ajf]

Thank you for the suggestions.
I will have a look at both and see what I can find on the cheaper alternative.
I guess though you bery much pay for what you get?
I may wait a bit and go for the Rode as it seems to be all round very good from what I read and would at least give me scope if I start doing more videoing.

FYI it is mainly vehicles of various types so assuming a directional mic like the Roade is the best type?