Herzly Cards is a web app service that allows the user to upload a picture, text and a destination address. The information gets stored in the database. Each order cost 1.99€ for postcards where destination address is in Europe and 2.45€ for rest of the world.
The app supports payments from paypal and credit cards (stripe)
Note: This service is no longer availabe but still accessible at https://herzly.com/en/cards