Are these sentences right?
He went to the country to rest from big city life.

The film is coming nearer the end.

She married him for the sake of making money.

You are at the bottom of our failure.

I bought a flower on my bottom dollar.

Question

Are these sentences right?
He went to the country to rest from big city life.

The film is coming nearer the end.

She married him for the sake of making money.

You are at the bottom of our failure.

I bought a flower on my bottom dollar.

Answer

You are at the bottom of our failure.
I think you mean: "you are the reason for our failure." You could perhaps say, "At bottom, you are the reason for/source of our failure."

I bought a flower on my bottom dollar.
I think Andrew is right that this is a very restricted phrase. Try: "I bought a flower with my last dollar."

Answer

He went to the country to take a break from big city life.

The film is approaching the end.

She married him for the sake of (making) money.

You are at the bottom of our failure. - What's your intended meaning here?

I bought a flower with my bottom dollar. (the 'bottom dollar' is not very used, other than the classic "bet your bottom dollar"