I'm curious about a uploader on my webshop

Hi guys,

I’m selling photo collages on my (shopify) webshop and i was wondering what are the opportunities to make a custom made collage uploader in it. Now the customers can mail me the photo’s and then i send them a preview back. But the best way is that the customer can make them own collage in the webshop.

Has anyone a idea at what for price i need to think ?