I don't collect knight LEGO themes, however I saw that whenever a knight minifigure or set is listed for sale (in my country), the price would be very high. CMF knight minifigs are also 3x times the regular price.

This is also true for listing on Bricklink, so I don't understand why LEGO discontinued the Castle themes since 2013, with occasional standalone sets/minifigs. I read that the demand and sales were low back then, but a few years up til now, isn't the demand very high?

On a side note, I do really wish the price for the set in the picture didn't go that high, it was a gift my parents gave me when I was little, but I lost/destroyed most of them, and really want to buy it again some day :(