Lavender/Lilac Bridesmaid Dress

My girlfriend is getting married this September 15th and I`m the maid of honor and I need help finding a dress! Since just recently engaged (May 5th 2002) I was asked to be in the wedding 7/1/02. I`m looking for a lavender or lilac bridesmaid dress in a size 6 for me and size 14 for her cousin. I`m in Chicago and even though I have found a few styles I like at department stores, I haven`t been able to find this color in both sizes yet. Our budget is $125. I would prefer off the rack since we don`t have a lot of time nor money to rush an order. I already looked at Nordstroms, JC Penney, Chadwick`s web site in addition to the department stores in my city. They were out of those colors and or sizes. I would appreciate any suggestions.
Thanks