You can make your own, ya know..

You can use the Open Book prop, map it with a picture of you and your significant other.. and on the 2nd script you can place a link to your (or your partners) SC email. It's not the fancy version, where you click it and it zooms in.. but this one gets the job done.

When your guest clicks the book, it opens an email to you, and they can put their wishes there and send it. It's simple, but it works. You can share the congratulatory emails with your partner later.

I had purchased one of those that you zoom in with for my 3rd wedding, and it was frustrating to use. So I made one using the Open Book.

Hi

if you're still interested in the guestbook, I can create a customizable, without adds or advertisements, with logos and images that you need

Here is a live demo: http://gtbk.ncontraste.com/gbdemoen.php