Print On Demand - Ecommerce

Hi, My current project [login to view URL] need a revamp, The current website allows customers select a template, add their own text, and pay me through paypal. The website uses [login to view URL] website software for ecommerce and CMS, I want to redesign the website so customers can design the invites themselves. I want to use the [login to view URL] software a for ecommerce I know it inside out for my needs. I am will to remove all my current templates and start a fresh, I want the customer be able to see text update the text in real time (or after they click submit) I would like the customer to be able to resize/change fonts/angle text (if possible) maybe through Ajax/Flash I would like them to be able to choose premade png/gif/jpg graphics to add to their designs (and add their own) again maybe Ajax/flash I need the client to see a web ready size PDF/JPG proof, approve the design then proceed to checkout as currently is. I need the output file as PDF or High Res JPG for me to print, Note: I am currently rebranding the website with a new logo/domain name/look, and as a graphic/webdesigner I can do this myself, It is the back end system / programming I cant do. I would consider switching to OsCommerce or another Major ecommerce software back end system, but have preference for [login to view URL] I would prefare someone with previous experience in Print on Demand Ecommerce systems. Thanks Stephen