Balance question - Rare spells vs Very Rare spells

[Settemio]

Why do Rare spells take up MORE of a Zone's Treasure Budget than Very Rare? Shouldn't it be opposite?

[GMBarak]

a very rare spell is equivalent to finding a book or a retort, although I think a book or a retort is worth much more, The question that you should be asking is: why does a book/retort costs only 800 budget? When I asked Seravy about it he said that he want to give the AI player a better chance to finding these treasures. To his claim, setting a higher budget will give an unfair advantage to the human player.