If you want to spend a pile of money and he's into cask beer, you could get him a beer engine.
If he likes barrel aged beers and you think he'd like to fill one himself, you could buy him a new barrel. Alternatively you can get him a stand to hold a barrel and let him find a used barrel on his own (since you don't know if he'd prefer red or white wine or bourbon or whatever).
Or maybe just get him something for the brew cave rather than brewing gear itself. You might be able to find a nice decoration - sports memorabilia, neon or a framed beer sign, autographed picture of John Palmer . . .