I have an alternative way of recalibrating for you:
Assume a wizard, that in the late 700s when vis and high magical auras were much easier to find, a magus with no corresponding virtues or flaws, studies from vis 2 seasons of the year, in an aura of 10. Art scores top out around 100 for such a specialist. I've sat down and completely rethought how the order works based on this and some other posts:
1.) The Peripheral Code would have multiple rulings on the protection of the trade of books
2.) In a thread on the Order's population, it was pointing out that the Schism War was a catastrophic event that would have reduced the order to about 30 or 40% of the previous size, and I add, reduced the order's ability to protect magical sites, in fact, probably much was destroyed intentionally too.
3.) The best books are old books, written at a time when vis was much more plentiful
4.) So there is a collection of surviving covenants from before the Schism war now "the autumn and winter covenants" that have the best books in the Order. Everyone since then is trying to get copies of those books, the more powerful of which will likely never be rivaled again.
5.) It makes complete sense for Hermetic Art books to cost vis to make and can only be written by a Magi, some exceptions for failed Apprentices.
6.) Covenants would have reciprocal agreements of mutual study i.e. study from my powerful book, and I get to study from your powerful book
7.) There would be some kind of rating system to measure books by
6.) The "base" books accessible under core rules are the crap magi are ok freely trading or giving away to new covenants
8.) New good quality tracti would be highly valuable