Any place that sells luggage would likely carry men's wallets. Unfortunately men's wallets are hard to shop for. It's hard to find a good selection and one's that are not complete crap.
I'm in love with my current wallet but it's falling apart. I've been looking for ages for a new one of the same design. It's the size of a credit card and does not unfold. It has a strong earth magnet built into the backside that your change sticks to. If anyone knows where I might find another one... let me know.
I use a very small wallet with a money clip that goes in the front pocket. Not sure where you get them in US. I work and travel internationally and it is a good way to prevent pick pockets. Once you get used to it a guy will never go back to that wad of stuff on his ass.
It's tough because if you buy him a wallet that's like $5 (not saying there is a wallet that cheap) or buy him one that's over $1000 (again, exaggerating), he may feel like 1. You don't care about him enough..or 2. You care about him too much. He should give you a spending limit so that you know how much you are allowed to spend. Even then, it's risky because sometimes, like with women, what we say, isn't always what we mean.