It's a photobook to celebrate 10 years of touring, not her 10th Anniversary, I think. The description says that the book will contain photos from all her live tours, not just ~NEXT LEVEL~ and ~10th Anniversary~ tours. So I gues it'll be pretty nostalgic.
4500yen for a photobook and a shirt is quite affordable, actually. Her Tour shirts normally go for 3000yen each already. XD