iPad got wet inside backpack. It still works but the screen has water marks.

I was walking to class and it rained. My iPad got wet and now it looks like it has water inside the screen. It still works just as normal, except now the screen looks like that. I took it to the apple store and they said water damage is something that can't really be fixed, but rather get replaced instead, so the cost is about $419+. If I continue to use it the way it is will anything bad happen? Alternatively, can I go get it fixed somewhere else?