Business idea and evaluate the difficulties to be First on G on specific terms

I am looking to buy a domain name.

This domain is related to a specific search on google which generate 33 000 search per month.

The number of search for this specific term is pretty low but it has high value.

My idea is to buy the domain for this specific term and be in the first position on google and generate leads.
I worked in the leads industry and I know how to monetize that.

Here is my thought process:
33 000 search on google per month

- conversion: search vs expected visitors for the first position in google is 18% (source seomoz)
If I am in the first position for this term I can expect 5940 qualified visitors per month. (33 000 x 18%)

- conversion visitors vs clients (for me visitors who request more information) : 1%
Usually it's around 2% but I prefer be precautious and take 1%
5940 x 1% = 59 visitors who request more informations.

I think I can sell these requests between 30 and $100. This means I could generate between 1 770 and $5 600 per month.

But how can I evaluate the difficulties to be first on G on this specific term? Is there some tools to help me?

- The URL of the first site on G on this search doesn't match this specific term
- This site is not focus on this term (no description and keywords match)
- The others sites (position 2,3,4) are big generalist not focus on this terms but tough competition

What do you think?