Buddy and his friend have no money, so they make each other kites. Although, we know that they would have liked to have bought each other something else entirely.
Buddy says he wanted to buy his friend a "pearl handled knife, a radio, a pound of chocolate covered cherries..."
Each of these is significant in their own ways. The pearl-handled knife is something that would be useful, but it is also very expensive and extravagant, given their lifestyle. The radio would give his friend a connection to the outside world that she does not have except for him. He tells us she does not read, except the comics and the Bible, and she has never seen a movie. She is not someone who leaves the house often, so a radio would give her a connection she does not have. Finally, she once had a chocolate covered cherry and swore she could live off of them, she liked them so much. Again, these would be extravagant and a real treat, given that they have to scrape for so much.