This is definitely his work, but you have to understand that not everything an artist makes is worth the same price. This is a pretty simple piece. If someone's paying real money for this it is for the signature (which I could not notice in the pic you posted).
Now, what I mean by "simple" is not that this isn't a nice picture. I mean that the detail involved in making this painting is nothing compared to some of his other paintings. I am almost positive that he did not need the "two perspective method" for this painting. When people pay money for a painting you cannot just throw out a price, it most be according to the elements entailed in art work.
