I was introduced to Blume Boxes by way of Courtenay Lambert and I just adore them. They come in tons of colors and the creative possibilities are endless. I know Courtenay delivers all of her bouquets in them but I'm sure any florist would be able to get them. You can always order them off the website as well.
The best part? Pop the girls' bouquets in them and presto - instant fabulous (inexpensive) centerpieces!