Web Based Vector Editor

Hello, I am creating a website for my company that creates vinyl banners and signs. I would like to use a web based image editor for visitors to create their own designs and the designs be sent as a vector image to me to be able to blow them up to the size of the banner. I am having an extremely hard time finding such a program... would I be able to use Gimp for this? If not, does anyone know where I can find one?

Thank You