Ignoring sewing skills/ cash flow issues/ laws of physics... describe your dream ballgown.
Ooooh.. good question!
It would have to be red, no question..
If money and time and sewing skill were no object, I would probably go all out and get an exquisitely re-created 18th french ball gown, no expense spared, silk damask, embroidered to within an inch of it's life.. with all the underpinnings, shoes, clocked stockings - and of course an appropriately over the top wig - one of those nice little numbers with a ship sailing on a sea of curls or something.. Of course just as ladies did back then, I would need several matching bodices for different times of day, and if I was really going all out, I'd get some matching skirts too - say a natural form bustle and a caged bustle with the respective underpinnings...
It would be a versatile and extravagant ensemble! :)