Well two things. CUP decided to stop publishing books on amateur astronomy last year and Willmann-Bell have also closed last month. These were two of the few providers of quality books for the amateur astronomy market. I don’t think anybody could call Springer a publisher of quality amateur astronomy books due to the poor quality of the printing/layout and the poor quality of the content of the majority of their books. It seems that we are going to face more self published books.
As always your mileage may vary.