I'm not shocked as I read your history on another thread and sympathise.
If you can be sure the 9 year old will get the gift, perhaps via his siblings, then get something.
If not, you're wasting time, money and heartache.
Do the older children give you any hope that their brother (obviously still influenced by Mum and that's okay, he's trying to be loyal) will be allowed to keep the gift?
If you bought a book (Diary of a Wimpy Kids is very popular) would he read it?
If you send a book token, would he be allowed to use it.
These are the vital question which will help you decide.