Orb of Power is super cheap and pretty much the go-to late-game item.
Demon in a Bottle is a great thing for all the soldiers to have, and you can bust out more forces when required. But its not for a wizard.
An elixer of life is pretty much essential, but nobody carries it, so its not for a wizard, even though it is.
Scrolls of spells you don't know are always good, try to carry a few if you happen to have them.
Wizards with Fight+5 very much want a +2 Hand Weapon and offhand dagger.
Fate Stones are amazingly powerful, and the Boots of Speed. Gloves of Casting are great if you aren't a witch, and useless if you are. Use them for summoning demons or mind controlling people.
And whatever slots you have left go to Robes of Arrow Turning, rings and cloaks of protection.