I am a member of the Rue La La Boutique. They have a boutique open now with some wedding gowns perfect for casual weddings, including some designs by Nicole Miller. It is called Style. I Do! For Bride, Groom, and Guest.
There are several gowns under $500. I especially love the one pictured to the left. Even if you are not looking for gown, still sign up for Rue La La. It is a great opportunity to get designer clothes for less. I love it! Click this link to signup
Rue La La.