Great sharing, I share my bit as well.
It is possible you buy those books twice per level (at least on low levels <10)
Restocking
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As soon as you enter Cyseal, go straight to recruit Madora and Jahan. They will be at lv 3. By the time I did that when I was still level 2 and there was a XP gap between them and my hunters of around 3000 EXP. If you skip all the exp thing at the beginning (tutorial cave, exploration exp, Ishmashell) you should have an even larger gap, giving more room to manage your EXP gain and separate levelling. So after the Teller is unlocked, you can restock every time using Madora/Jahan first then your hunters, offering 4 books per level, provided you have the money.
Are you sure this actually works? I've never been able to get a vendor to restock with a level difference like that. It seems to check character level on barter, and only restocks if it's greater than current item level on the vendor. Having a companion check and buy the stat books at level 12 and immediately checking with lvl 11 player character (having not previously purchased any stat books at level 11) does not result in a respawn, at least on the current steam version. Are you using GOG / an older patch?
