The opening of O. Henry's story alludes to Della's frugality with these words:
She had put it aside, one cent and then another and then another, in her careful buying of meat and other food.
Della had amassed the sum of one one dollar and eighty-seven cents by bringing scrupulous awareness of her spending on groceries for herself and Jim. Jim was being paid twenty dollars a week, and their furnished room cost them eight dollars a week. From the remaining twelve dollars a week, it is reasonable to assume that Della was given a food allowance. She clearly stretched it as far as she could, putting aside a cent or two for months and selecting what she bought with great care. Ultimately, she had saved less than two dollars by the day before Christmas and had earmarked that money as her fund to purchase a gift for her husband.