I wonder how many he signed. There are still signed copies available. Tim Burton signed about 50 books for his exhibition at the Design Museum. They sold out within minutes.
This is a very nice item but that autograph is appalling - a forger's wet dream.
There are going to be a lot of fakes on eBay pretty soon so keep your receipts and paperwork with the book. Without any statement of limitation etc on the book it will be very difficult to move on if that should ever be your wish.