Hmmmm...the links didn't work for me when I tried clicking on them again...weird :p Anyway, if you go to nordstrom.com, then click on women then "dress shop" on the left hand side, it'll take you to the page will all different kinds of dresses.
I found the girls' dresses in the "bridesmaids" section...most appear to be 50% off right now. I'm not sure the style or color you're looking for, but here are a couple examples...the three are $48 (I got the fourth pic in lilac for $35, but right
now they're $53...still a good price and great quality too):

There's a few websites that can guarantee the same dye lot if your order them all at once...like a salon. I've heard that most salons can be much more expensive than sites online because of overhead costs and all that if you decide to go with
Alfred Angelo. I've heard netbride is good, I had a great experience with plussizebridal.com (where I got my wedding dress...they have normal sizes too) and houseofbrides.com also seems to get good reviews and they have really good sales from time to
time :)