Without master inquisitive, it takes 50 mins to grind for a legendary book and probably 1 hour and 30 mins or more for a mythic book. Since cosmos players get books for free and they believe it is not worth opening the books (as its a rare chance that youll get a good enchant), its sold for around 8500/15000 respectively. I don't know the average time a player spends on the server a day, however it is not worth using your entire play session for the day to get 1 book, where you can instead buy a book for a lot cheaper and with less effort/time. Making the ability to purchase legendary/mythic books in /ce a unused feature. Therefore I was thinking maybe the legendary book exp price should be reduced to 80 lvls and mythic books to 100 levels. Making it also fairer to non donator players who still have to put time and effort to get these books, but this way it wont be unreasonable.