Image gallery and ecommerce?

I need to set up a photography website with image galleries and the ability to purchase individual photos. I currently have a theme using a PrettyPhoto Lightbox Gallery. I was wondering if there is anyway to introduce the option to buy different photos from the gallery in different sizes?

This is my current gallery.

https://www.jmaxphotography.com/?page_id=636

I dont want all the images to have the above options, only selected ones.

Anyone have any ideas? I’d really appreciate some pointers! Thanks!