Try thredUP! This link gets you $0 off must-have styles!
-TIP: Use thredUP to buy all your bridemaid dresses! Pick a color palette, set some general guidelines, and pick out pretty dresses with your bride squad. thredUP has amazing options up to 90% off retail (like this gorgeous Ann Taylor number - 81% off retail!). Also, cocktail dresses are a great thing to buy secondhand, because they've typically been worn only on a few special occasions.