This purple kite is one of my favorite designs and it is known as the 'McAlister Box' or 'Diamond Arch.' This design was first featured in Drachen Magazine in the early 90's as well as in the sky gallery of Kitelines Magazine.
It was designed by Tom McAlister (that's me

) and the one shown in the photo was build by Drake Smith.
Your photo is from the
www.HighlineKites.com website.
Drake made another version this McAlister Box kite design which sold at the AKA auction in Florida last week.
This kite is not commercially available at this time.
Happy Flying!
Tom McAlister