I'm from India. I was looking for a service like this but without sending me a physical book part.

I'd use this at @ $10 price point if I'm able get downloadable a4 coloring pages from a picture. It would be great. Also this way your customer base becomes international.

$10 for 20 pictures is a good price point for me. Pretty expensive but I'd still go for it.

I'll implement this today.

Edit: I've implemented this! It's a lot of code changes so I hope I didn't break anything.