I'm not going to pay for DD's. I'm remaking her Christening gown (which I got for $15 at Marshall's.) It is appliqueed Battenburg lace over linen, and is really long and has a heavily gathered skirt, so there is enough fabric to do it. When Communion is over, I'll cut her a hankie from the lace to keep for her wedding. I kind of like the symbolism of having her wear versions of the same gown for all three of her major lifetime "white dress" religious events.
It's fancy enough for any little girl to love at age 7, and I'll cut the bodice in a style that she likes. (My mom did the "basic" thing with mine, too -- there was nothing special about it at all. I wore it school many times that year.)