I agree with the slippery slope. Shouldn't this give wizards the incentive to make sure that their spells are safeguarded from other wizards, even if someone bypasses the wards on their spellbook? In real life terms say I had a notebook filled with notes from calculus, geometry, physics and geology, between my diagrams, comments in the margins, short hand and really shitty handwriting, equating that to a spellbook Id be hard pressed to say just any wizard could pick it up, read and copy it. This would also deter other wizards even wanting someone elses spellbook. Think 5E simplified the system for wizards reading, learning and copying spells. I suppose ultimately the laws of supply and demand will dictate what the spellbook is worth. Seems to me buying a hot spellbook in a dark back alley would be like buying a .38 Special off a street corner.Feels like creating an objective price on this creates a slippery slope no matter how you come at it. And probably because this shouldn’t happen in normal course: specifically, it seems to me that wizard guilds do not want spellbooks being sold in unregulated markets (think doctors and prescription drugs). With spell scrolls being a historical exception (and those theoretically being one-time use only).