Custom Product mods to Joomla / Virtuemart

I am building a site (Joomla / Virtuemart) to sell customized promotional items. Pens, calendars, etc. The most complex product is custom postcards. The user picks a template with from 1 to 8 images, uploads their images, uploads their logo and adds a message and contact information. We need to capture their choices and create an order for the vendor to produce these. A competitor site is here: [login to view URL] See how they prompt the user for information. We want to save this and show them a mockup of their postcard, then sell it to them while saving their selections with their order information. To get this job, tell me how you are going to do this. In detail.