its a bit last minute, but maybe you could ask if they're listed somewhere.
I've been to two weddings here. The first one, I asked around, and everyone said not to bring a gift (and no else appeared to either). The second one, the bride and groom asked for no gifts but if you wanted, they were accepting cash to put towards their honeymoon. I wasn't at all comfortable giving money so we got them a bottle of French champagne. At that wedding, I didn't see many people give cash...and no one but us bought a gift. The bride and groom never thanked us for our gift...maybe it never even got passed on!
If I were you, I'd get a nice bottle of champagne (even if they don't drink, it's always something nice to have around). But if you'd rather not, I wouldn't stress out about getting something last minute. It seems like people just don't put an emphasis on wedding gifts here.