How about a "celebrity basket" with small tubes of sunblock, and anything else you are thinking of adding. Sunglasses, and travel size beauty products come to mind. For another day you could do up a night time themed gift of small pillows ( maybe with lavendar for scent), an eyemask and play a soothing cd of music. This is all assuming of course that it's an overnight camp, but if it isn't you could skip the music.
If you can sew, it wouldn't be hard to make those things, but may get a little spendy if you need to buy too much. Some other little things you could do perhaps; bookmarks, a camp photo album, and little potted flowers.
Have a wonderful time