Costco now offers gift registry!
They recently started a gift registry service on the website, you can set up your own account for free and you don't even need a Costco membership. All you do is go through the website and select "add to registry" - whatever your registry may be! But, don't get your hopes up because you can't register for every item on the website. Don't expect toilet paper in bulk, but you can add bedding, furniture etc!