DIY wedding Web sites range from free to around $99 for a year. But as the old adage goes, you get what you pay for.
The free wedding Web sites offer basic design with few, if any, customizable features. You'll probably have to deal with a couple of ads on the page, too. (Someone has to pay for the site, right?) Most pre-fab wedding sites have packages available at different price points so you can upgrade to the one with the bells and whistles you want. The advantage of picking a service like this is that you don't have to have design or HTML skills. The downside is that you'll probably end up having to choose from one of their design templates, so you may not get all of the customization that you like.
A great way to find a service is to pick another bride's site that you like and find out what she used. If you want your Web site and your wedding invite to have the same colors and design motif, you'll probably need to hire a pro, which will cost you hundreds of dollars.