Hi @dimitrius154, thanks for your help.
I didn't really want to raise the price to ridiculous levels, because I didn't want Higher Tier CAs to be something that you just save a lot of money to buy it.
I wanted it to be more like something you achieve during the game.
I was thinking about putting one runemaster on the Great Machine Hall and removing the rest off the map, so rune exchange could only be a thing at the end of the game, when you are about to complete the main quest.
I Managed to remove all the rune masters by erasing their ID on creatures.txt, but I didn't find any file that specifies where the runemasters spawn, so I couldn't do more than that.
Do you know any way to make runemasters spawn at different locations without code alteration?