Save Money, Shop Happy!David's Bridal Soft Chifon Halter Gown

I bought the dress from David's Bridal and I don't have time to make alterations, my wedding is around the corner. They won't let me return it so I'm trying to sell it. The dress has never been worn, I bought it a week ago, the tags are still on it, and it's in a David's Bridal bag. I payed around $600 for it. I would like to sell the dress for $500 but will take best offer.