Hello,
I have read your project description. Shortly, I have made similiar project in ActionScript/Flash for some Polish company, but I can make it in HTML5/JavaScript too. Or if you wish, I can do some desktop application in C# or Delphi which will be connect with your site to load yours designs. I can do this application in 5 workdays for 350$. I can send you demo of my previuos similar project. If my proposition is interesting or you have some questions please feel free to send me PM. Regards.