There are two types of website builders you can use for your wedding site:
Generic Website Builders that also have wedding templates
These will usually charge you a monthly fee and will not have lots of wedding specific features because they're well, generic.
Weebly stands out with their free offer because they don't offer any ads (like most other will), but even there you'll probably want to spend a bit for a custom domain.
Website builders focused on weddings
These are the ones we will mainly focus on, and most will charge you a fixed fee. Interestingly, some will be free (like Joy or TheKnot), because they will try to upsell you on other wedding related spending, of which there's plenty :)