First months rent on his own apartment?
IMO, if you are asking strangers on the internet what to buy your kid, maybe it is time to rethink the whole gift giving idea. We stopped exchanging last year because no one could figure out what to get anyone. Grown kids with jobs buy what they want/need. So instead of stressing for a month on what to get, we have a relaxed holiday. Spend Christmas together, watching movies, etc.