They are the same stamp, and the perfs and centering do match the position 73 example on the Siegel power search. I can't imagine buying a stamp like this without an examination and without a cert from anyone. Certainly not from a no name seller with 4 items total for sale. $400,000 might well be much more than it would bring at auction today, depending on the exact condition of the stamp. Assuming that it is not just a color cutout from a catalog or a created computer image.