I remember a few weeks back finding a shop that sold some powerful wands that did 90 damage 100% of the time. But now I don't remember where I saw it, so I can go back and buy it. I've tried the shops in Marleybone/Krokotopia and Zeke, etc. (I'm not to Mushu yet) But I'm not seeing what I once thought I saw.
They haven't had a visiting shopkeeper (that I have seen) since February. You can find more powerfull wands at various boss fights, or take a look in the bazaar. I myself have purchased three wands: two 90 damage wands, and a 95.