BUILD A CUSTOM STICKER CHECKOUT AND PREVIEW FOR SHOPIFY

I am trying to find a custom product designer app for Shopify for a custom sticker website, but they are all very limited. - I need there to be pricing per square inch. - I need there to be quantity breaks. For example, the price per sticker goes down if they order 250 stickers instead of 100 stickers. - I need our customers to be able to preview their sticker right after they upload their image. The problem is, that we are offering die cut stickers, meaning there will be a white, contour-cut border around the image they upload when the actual die cut sticker is produced. Here are two examples of sites that do what I am talking about: [login to view URL] [login to view URL] If you upload an image (transparent background or white flat background) the app will contour trace the image and provide the customer with an accurate representation of what their stickers will look like. If this last step is too difficult and expensive, I am open to workarounds. For example, this site shows a simple preview of the uploaded image, but they send you a proof via email once it is ready. This would eliminate the step providing an automatic proof. Any advice and suggestions are much appreciated. I will not consider applications that have not shown that they are capable and understanding of what the project entails. Thank you very much for your time. Matthew.