My friend was very happy with the ones she got from ebay/China - she picked the dress, sent in all the measurements, and everything was perfect! And a lot cheaper than anything here. But make sure you find a reputable one if you decide to go down that route, because it's not as easy as going to Fair Trade if you have a problem

ETA - You could also look at catalogues, like UCW or Postie. From the sounds of it they might have something perfect if it's a beach wedding