First, have you looked at making the blades your self? Here is a link for a DIY 10' blade that is easy to follow ( http://www.otherpower.com/trips3.html ) just scrool down the page and there is a step by step on making the blades that you should be able to follow. You could just scale it up to the size you want.
Having them made on a CNC will require not only a CAD drawing of the blade that you want built, but also a shop with at least a 10 foot CNC mill with a fourth axis. Also hope that they have a low shop rate as this large of a blade would take many hours of machine time.