A pay to print button (and pay to download) option with a paypal payment gateway backend to receive payments would be good.
There's a number of print houses that provide an API and return prices for postage and handling and cost for orders and will print and post orders to customers.
If you are interested in this project please let me know or I will work on it independently.
I'm planning on allowing customers to provide their mobile phone number and email address for full-res photo downloads - they are notified to a URL to allow them to download their photos.
