The hunter, in an attempt to persuade Sylvia to reveal the location of the white heron's nest, says that he would give ten dollars to any person who could help him find it. For Sylvia, "No amount of thought, that night, could decide how many wished-for treasures the ten dollars, so lightly spoken of, would buy." The little family of Sylvia and her grandmother is described as "poor" in the third-to-last paragraph of the story, so I would imagine that the ten dollars would help, for a time, to put food on the table and in their bellies. It might help pay for some new clothes and shoes for the two of them. I would think that they'd be able to pay for some necessary items with this money, and so it might not really be used for the "wished-for treasures" Sylvia imagines if they truly are so very poor.