I would suggest jumping on this website with him, browse through some toys, asking his opinion all the while and casually start looking at anal toys. If he doesn't like the idea of you using them on him, ask him if he'd use them on you. After he sees how much you enjoy them, maybe he'll want to give them a try. And if he's not interested at all, buy a couple of toys for yourself, use them alone and store them where he'll see them.
I have to tell you that I tried this with my wife and it didn't work. She has zero interest in things anal. But, it might work for you.