I am unsure as to what I should suggest. He is Dick but he is not my Dick so I do not know what he likes.
I know that my Robin would like anything in the fast vehicle, interesting weapon, new gadget categories. But if he is super rich, he would most likely have all of those things.
You could give him something that is of the sentimental value to you? Is there anything you cherish that he would also enjoy?
On the lighter side of things, if I may be so bold. It would be appreciated, I am sure, if you gave him favors of a sexual nature. It seems that the human males seem to enjoy the having of the sex on a constant basis.