Water damage sucks big time, my advice, if you haven't already done this - keep your phone (turned off) in a nice warm place for a few days to dry out, see if that makes a difference.

If not, take it to Nokia, tell them what happened and see what they say. Sometimes you get lucky and they do things under warranty, sometimes you have to pay. Best policy is just to be honest. We are all human, we respond well to good experience, you don't catch a break this time, well, maybe next time.

The camera module itself is not terribly expensive, I'm not sure what country you live in, but for me it's about $70 USD give or take $20.