Check the contents of this thread, it's all here:

New update - new magic items > new trader cycle

Somehow there was only 1 BoH in the new cycle

SC decided to make it more BoH > just before the day and the work week ended for SC, someone manually updated the trader cycle code by replacing at least two, maybe three other books with a BoH [All the other books are 925 gems, BoH is 500 gems]

That person made a mistake: they changed the item name, but they forgot to change the accompanying cost in gems for the items
The change went live

SC went home for a long holiday weekend ....

The forums exploded
SC has acknowledged this, and as Darian stated: in the next maintenance it will be corrected - but they are working on some more things for that maintenance ....
Hope that helps