Letter asking to buy a person's house when its not for sale?

[Mike Shemp]

Hi All,

There is a house in our area that is not for sale at the moment, but we would like to buy it.  Does anyone have a good template/letter they would be willing to share?  

The purpose would be to purchase it for short-term rentals purposes.  We also thought about contacting a real estate broker to be the liaison for us or act in a buyer's agent, but wasn't sure about that either.

Any suggestions on how to approach this, or wording to include in our letter would be greatly appreciated!

SG