Congratulation Tom! This idea is a milestone if it's well continued in the future. A big step to more individuality, which we all are asking for. There is a big chance for you of course, as the people have to buy the clothes to create the own fashion. And also a big chance for all users. That's what I call a win-win situation. Even for those who don't create own fashion it will be nice to see different styles.
Tom, I read your post once more and now I've got a question: You write, the best idea will be added to the shop. So all users can buy them. What about the designer? Will he get a share? Is he allowed to wear his own clothes for free?
I know you're just talking about an idea – but I think these are two important questions.