I've got everyone's presents down but my 17-year-old brother's. He's a minimalist and doesn't like tat that he won't use and will just sit in his room, very particular about clothes and cologne/deodorant (the more expensive types) and he doesn't have any hobbies or interests other than gaming and being with his friends. Won't do experience days. He has a job and gets a steady wage so he's always got his own money and buys anything he needs. He isn't into chocolates and sorts either.
On top of that my budget is quite small, around £15. I really can't think of anything he would want or use.