I'm not sure if you would want to give anything to him, thats if he believes he has everything and is stuck up about it. if not, then you should give him unconditional love (but dont go too far like sex if ur not married or something) and u could just be the best friend he's ever had. you dont have to give him material things. maybe if hes like the rich type that only has friends for money or something, then what he really needs is a true friend. actually the best gift i think that u can give him is a bible. idk ur religion or anything but that is always the best material gift a human can give to another.
I doubt it that he has really EVERYTHING! Just give him your love and support. If you want to buy something for him..I don't know, try a delicious dinner or a trip to a lovely place he's never been to (not really an expensive trip)! :P