The Gift of the Magi is an excellent story on the scripture that states it is more blessed to give than receive, found in Acts 20:35:
I have shewed you all things, how that so labouring ye ought to support the weak, and to remember the words of the Lord Jesus, how he said, It is more blessed to give than to receive.
Truly Della is much more blessed giving than she is receiving. Now, with her hair gone, she cannot use the expensive combs. Likewise, her husband Jim cannot use the platinum watch chain. This story is based on the blessing of giving, not receiving.
Throughout this story, the art of giving is highlighted. In fact, it is compared to the Three Wise Men who gave abundantly to the Christ child. They wanted nothing in exchange.
While the story reflects a giving heart, it should be noted that Della and Jim are amazing people. They give unselfishly. Their prized possessions are the first thing they give. Della gives her hair and her husband gives his gold watch. The gifts they bought in exchange cost more than the dollars they paid. The gifts they bought in exchange cost Jim and Della heart and soul.
When Della and her husband parted with their prized possession, they proved their magnanimous love one for the other. This story is more than a fairy-tale type love with a happily ever after ending. This story teaches the reader the value in giving up something that means so much in exchange for something to make another person happy, even if it makes one sad. The ending of this story has both a sad and happy ending.
Who gives like this? Who would give up something as precious as one's hair? Della does. She gave up her very adornment. Likewise, Jim gives up a family heirloom. He parted with something that had been passed down through the generations. It cannot be replaced. When the reader learns to give sacrificially as Jim and Della have, the world will go lacking nothing. That is the point the author is making.