I am archmage at my college I only bought Fury tome so far but the illusion instructor doesn't have paralysis spell book. I've only see scrolls of paralysis. I am lvl 26. Also where can I find a staff store?

Look in Labyrinthian, there's a [censored] ton a tomes in there.

Paralysis is an Alteration spell this time and it doesn't become available before your Alteration skill becomes 75.

Paralyze is an expert level alteration spell. It will only show up when your alteration skill is high enough.