Sandwich top oud

Hi guys,
yesterday i discovered the sandwich top oud in the khalafoud web site.
It's 40% lighter than a traditional soundboard, allowing the plate to resonate to a much greater degree than a traditional all-wood face.
You can find here some pictures and sound samples :
http://www.khalafoud.com/sandwichtop.htm
After watching a video sample,i was very pleased of his clean bass and incredible resonance.
I wanna thank the great luthier and oud player Mr Jameel Khalaf Abraham for this invention.
But how much it costs ?