Which of the following uses the superlative form of a quantifier with an uncountable noun?

I think I would like to buy a book with fewer pages.

The book with the fewest pages is the cheapest.

I have little money to buy books because I am saving for my holiday.

I have less money than my sister, so I can’t buy an expensive book today.

I bought the book that cost the least money because I am saving for my holiday.