The Mastro name probably helped for several reasons. There is a lure associated with owning a piece that belonged to a prominent figure from our hobby. He also had a great eye for quality unique pieces that helps a buyer feel secure in making an "investment".
Jerry made an excellent point regarding scarcity. This is absolutely the best offering since the Halper auction and many collectors will break the bank for that ellusive piece from a want list.
I would like to know how many buyers made a purchase framed as the following: "Honey...all I want for Christmas is...".