calling all frugal friends!

I need help finding dresses for Mattie Leigh, Allie Grace, and two of my nieces...we need a 2T, 5, and 10. My hope is that there is a dress out there that will come close to matching for all four of them and work for both Easter and my brother's wedding in July. I know the wedding colors are close to lime and turquoise, so if the dresses have those colors in them, it'd be great. Otherwise, I'd like a white/cream dress that we can embellish with a sash or flowers in those colors. If any of you know where to look, please let me know.