While we're on the Christmas present tip (I've been posting a different, affordable gift idea a day all month in case you've missed them), this could be the solution for that teenage niece, just-out-of-home-er, or godson on the list.
A lava lamp: what do you think?
While I probably wouldn't have a lava lamp at home myself these days, I do have a very soft spot for the things, as illustrated