In the story, "Gift of the Magi", Della sacrificed her hair to buy her husband a platinum fob chain for his watch as her Christmas gift to him. Unknown to her, James sold off his watch to buy her a set of combs she has been lusting upon for so long.
Both items were of great value to each of them but they each sacrificed it to buy gifts that they believe will give happiness to each other and to show how much they love one another.
Sacrifice is a virtue to be valued because it is one way of expressing deep love to your loved ones. You would rather suffer a bit of self-disappointment to make your love ones happy.
