This is extremely common. We're considering doing this in lieu of a registry for our upcoming wedding, even we are also saving to cover the cost of the honeymoon. For some reason, "buy us dinner on our honeymoon!" is sold in the wedding industry as being less tacky than "Any small amounts of money that will go towards the Thing We're Putting All Our Resources Towards as a New Family (i.e. homegoods, moving, first house, family car, needed upgrades/repairs for everyone to live together, etc. etc. etc.)" Posting it on Facebook where many of the people who are 'not attending' were NOT INVITED? ew. And dude, if someone isn't attending, they either will or won't give you a gift. They know how to find you. People who ATTEND do not have to give you a gift, jeez.