Allow me to give an opinion on a book that I know well. This volume presents a "Silmarillion" more authentic than the book came out in 1977 under this name: Christopher Tolkien has also explained how he was led to complete _The Silmarillion_ with the help of G. Kay, the request of his father, to answer an urgent request from the from readers. It contains explanations of the hand of Christopher Tolkien, but it is indeed a book of JRR Tolkien, composed of texts submitted by JRR Tolkien Christopher Tolkien. This book contains texts and stories that we knew absolutely not, even in previous volumes. Recall that a book with color illustrations and black and white reproductions (more than those of the English version quality) is costly to the editor, which may explain the price.
Vincent Ferré ps: since I have to select a note ... pps: and if I give my personal opinion, I said that this is probably the largest volume in the top 4 of the series.