Coder for Photography Template Site

I need someone that can code a website to work like this: [login to view URL] I am a photographer/designer and I sell photography templates that other photographers purchase off of my blog ([login to view URL]) and pay through paypal. I upload the files through [login to view URL] and then send them the link once they have paid. Although it's working for me I would like something more professional. I need something that is automated, they can add the templates to their cart and pay online and then download their Photoshop files instantly.? That is my project, I need someone to code this using Google check out option or paypal, either one is great and then for my buyers to be able to do the instant download of large files.