Keyword value question

Hello, I don't understand one thing, so I hope that someone could explain me.
Ok, I found good keyword with low competition (Match types: Broad):
h**p://img252.imageshack.us/img252/2713/22341593.jpg
These two are same, only different is "s" letter.

Now I searched again, but Match type: Exact.:
h**p://img405.imageshack.us/img405/631/48419815.jpg
So estimated avg. CPC droped from 0.59$ to 0.05$. What that mean? Why this happens?

And one more question: when I search keywords which I need to use Match type: Broad or Exact? Because in first picture keyword without "s" has about 12000 global monthly searches and in icture two the same keywords has only 1300.

P.S. Sorry can't post normal http links

globals naturally have a higher search volume than exact matches and exact matches would be cheaper too if you buy adwords

dont bother about this question just take as many keywords as possible

furiouz said:

dont bother about this question just take as many keywords as possible

Click to expand...

I wanna create micro niche website with that keyword and i'm confused what to do
P.S. Is it worth to create micro niche website with these keywords?

No more answers?