Help me find a cute, "cheap", dress for e-pics?

I'm having a hard time trying to find the "right" outfit for my engagement session in June. We are going to a Bike Trail to shoot them... The bike paths have trees hoovering both sides, and bridges, etc. My fiance will be in a suit. I am looking for a dress to pair with my red heels. I have been looking everywhere!! :( Any help?