Add images to a lightbox

I am working on a site for a client who is a photographer, as well as selling stock photos (both his own and other photographers’). He would like to have the capability to have visitors add images to a “lightbox” similar to iStockphoto, etc., save the lightbox and then contact him regarding purchase. In spite of lengthy discussions, he does not want to sell via his website.

Is there a plugin that will add this functionality to the site or is this something that will need to be coded-

Looking forward to recommendations and suggestions-thanks!