(Note: I am not sure if this is posted in the right section, so moderator, please feel free to move to right section. Thanks!)
We have a natural latex rubber duck
We use small metal bowls and wooden bowls/cups (like play kitchen size) for water play, pouring, etc
We have a number of cotton terry cloth hand puppets for the tub (wash cloth material - can be thrown in the washer)
We also have a couple wooden boats that we've had for over a year and they've lasted just fine. We have this one among others like it.
Another consideration with bath toys in addition to what it is made out of, is to avoid bath toys with holes. Water gets inside, it never fully dries, and then mold and bacteria grow and mix with the fresh bath water at every bath. So if you do find a natural rubber duck, make sure there is no hole (not a squirt toy).