Priceless butterfly

David Graas created an accessory called "priceless butterfly". There is no price for this item; a customer determines the price, and buys the butterfly after writing the price on the tag. http://www.davidgraas.com/.
It is a cool concept. It s almost like putting a price tag on your own self-worth. From marketing and sales point of view it is a smart idea too. How many people are going to miss out on the opportunity to determine their price and make the buy. Also I wonder if customers get to see the old price tags for comparison. It is priceless anyways.