I agree with Miriam.

We celebrated our anniversary on the PG October 2nd and the ceremony was very nice (and free!)and you do receive a printed invitation. Just make sure the travel docs indicate they are on their honeymoon and it wouldn't hurt for them to stop by the concierge desk once they are onboard to remind them so that they do get the invite. The ceremony was for those celebrating an anniversary or their honeymoon and was conducted at sunset on the deck as we were sailing away from Bora Bora. They had champagne, cake, and wrapped each couple in a Tahitian quilt for a photo op ($12.95 for the pic). Earlier in the day we received in our suite a small anniversary cake and champagne. And there was always a small fresh flower arrangement in our room. I honestly don't know what you'd be paying $300 for. Everything is all-inclusive with 24-hour room service so they can order anything they would want delivered to their room (and better choices than just a few canapes). IMHO the $300 would be better spent on some nice excursions of which there are many to choose from.