PHP code to save backup images of website pages

Budget: $100 to $500

Hi -
I need to outsource part of a job I am working on. My client needs every edition of every page on his site to be captured as an image and saved to a backup. Part of the site will use WordPress, but another section, for registered users only, will be a custom php application. 
I am looking for someone to create this image backup piece. All the way from capture of each page edition (every time the content of a page is changed) to storage on amazon's s3 servers. 

Your code should be well documented and transparent. I like efficient.
I would like to see a sample or two of your work, either a live web application that you created or at least some code you have written. A reference from a previous customer will make you extra special. 

PS. the budget range is just a ballpark figure.

Thank you