In *The Hunger Games*, when the tributes are in the arena, people on the outside can buy gifts for them. It's said that the usefulness of items increases their cost, along with how far into the Games the gift is purchased. But how does this economy work? How can the Districts, which are kept in poverty, afford buying any gifts? Who pools the money that goes to the gifts, and who selects the gift? Where does the money go when a gift is purchased? Do the Gamemakers set the prices?

I don't believe these questions are answered within the books, so I'm looking for information the author revealed in supplemental materials or interviews.