I checked for 3 or 4 times and no staffs or wands appeared. I guess, the odds should be changed a bit.
Every NPC has a certain set of items they always refresh along with a few unique/purple loots that they won't restock.
For example, Nebora, the one that get rid of your collar, always has a green ring for sale. This ring will be restocked every hour.
There's really no NPC in fort joy selling a super good mage stuff. The closest one is the Lizard in the Elf cave who sells Warfare books. He sells all element of Staff and every time you level up, he restocks a new one that scale along with your level. However, none of them are magical so you're only using normal-quality stuffs that you can also attempt to create by combining branch + Shell, which will create a new staff that is as strong as your current level (level 4 craft level 4 staff)
If you really want good one, you will have to get lucky with chest because there's only a few green-wand hanging around in fort Joy for mages.
On the topic of HP, doesn't Classic mode give you an extra health which doesn't scale with con? Probably has to subtract that bonus health part first.
