‘Ave Maria’ is probably one of the best known songs ever–it is EVERYWHERE! Seriously. Go to a bookstore–Books A Million, Barnes and Noble, etc., and they will have a music section. Look for a wedding book, check to make sure it has Ave Maria (if it doesn’t I’d be SHOCKED) and BUY it. Chances are good you’re going to need it again. Some classical anthologies may also have it.
I don’t actually even PLAY the piece and I have at least two versions.
If you are picky and want a harp arrangment, get it airmailed from a harp center or a music store. Rhett Barnwell does a nice arrangment, and I’m sure there are other versions also.
Good luck. And I am sure you will find it somehwere.