They have several items in the shop onboard of various prices. We like getting small 'models' of the ship or magnets.
Another idea is to have her mail a postcard from CC. Keep in mind that it will take a very long time to reach home though since it is not part of the USA.
Something that we took home for my kids friends was the lotions and shampoos from the room (they had Disney Characters on them, although last time we went they didn't have these, but I have since heard they are back---but I am not sure).
DJ