Search in magazines and online sites for bridal shops run sales. Most of these stores like David's Bridal and Filene basement can usually have great sales at certain times during the year and catch them early worthwhile. Also check local department stores. Again, you are not restricted only picking a wedding dress in particular (such as might occur with a high price tag). Instead of an evening dress that you can change and turn it into a perfect wedding gown with only a little more fancy look.
Another good place to find good deals on wedding dresses, if on a tight budget is ebay.com. The returns rewarded hard work, the time to go through the site to a dress to find not only within your budget take, but nice and does it have for you is the right way.